Winston:  Winston is not much of a threat to Zarya.  If Winston leaps at you, simply use a Particle Barrier to protect yourself from his Tesla Cannon or melee attacks.  A good Zarya player will also be able to protect any one of her allies that Winston leaps to with her Projected Barrier.  Zarya's Particle Cannon at 0% charge without a Particle Barrier will out beat Winston's Tesla Cannon in a 1vs1 fight.

Unfortunately, Winston's Barrier does block both of Zarya's Particle Cannon attacks (both her short range beam and medium range explosive charges).

Zarya's ultimate Graviton Surge is somewhat deadly to Winston since he has no way to escape it (his Jump Pack wont let him escape it), but Winston can put down a Barrier to block shots from hitting him and his allies stuck in the surge.  Zarya's Graviton Surge becomes especially deadly when she traps Winston into it while his ultimate Primal Rage is active, making Primal Rage totally useless then.

If you can't use a Graviton Surge to trap a Primal Rage Winston, then use Particle/Projected Barriers to protect you and an ally from taking damage from it, even though Primal Rage will still knock you away from him.

Genji:  Genji's Deflect does not work on Zarya's Particle Cannon Beam, but Deflect does work against Zarya's charged particle shots.  For the most part, Genji will be a distance from Zarya throwing shurikens at her.  If Genji gets close he may do Swift Strikes at you (that does 50 damage).  Just keep your short range beam on him while taking cover, and use a Particle Barrier to further protect yourself from him.

Be careful launching a Graviton Surge around a Genji as he can Deflect the initial black Graviton Surge projectile causing a Graviton Surge for Genji's team.  Also Genji is one of the few heroes that can escape out of Zarya's Graviton Surge with his Swift Strike ability.

Genji's ultimate Dragonblade happens to be deadly against Zarya as her poor mobility makes it hard to run away from it, although a Particle Barrier can be used to protect you (or an ally) from it (if it's not on a cooldown).

Mei:  Mei's freeze gun is less effective against Zarya due to Zarya's Particle Barrier.  A Particle Barrier will stop the freeze build up.  With this in mind, when coming face to face with Mei, try to wait just a little bit before you are about to get frozen to use your Particle Barrier, so you can survive longer.

Zarya can also save her allies from Mei's freeze gun with Projected Barriers.  If you see any of your allies getting attacked by Mei's freeze gun, just throw a Projected Barrier on that ally to save em.  When your Particle Gun is near fully charged, it will be a close tie between killing Mei from full health and she freezing you.  This is another important reason to know how charged up your Particle Cannon is!

In 1on1 fights, Mei's Cryo-Freeze heal is no threat to Zarya, as Zarya's shield will regenerate quickly while Mei is frozen, thus making things even.  Although Mei can position her Cryo-Freeze so it blocks your explosive charge shots from hitting her allies.

Since Mei is usually right in the back with her teammates, she is usually in a targetable spot for Zarya's ultimate Graviton Surge.  While trapped, Mei can put up an Ice Wall to protect her allies that are stuck in the surge.  Mei can also use a Cryo-Freeze to avoid any AOE damage thrown her way, while also potentially shielding any of her allies behind the Cryo-Freeze.

Mei's ultimate Blizzard can be countered by using a Particle Barrier, and a Projected Barrier on an ally in the Blizzard as well.  The Particle Barriers will stop the freeze effect and let you walk out of it safely.  If a Particle Barrier is not available, then Zarya is out of luck due to her slow mobility.

Lucio:  Lucio will mostly keep his distance from Zarya while shooting his Sonic projectiles out at you.  Sonic projectiles are somewhat easy to avoid and you can even soak up the spam with your Particle Barrier to easily charge your Particle Cannon up.

Zarya has multiple ways of countering Lucio's fast movement.  Because Zarya's explosive charge shots do AOE damage, it's much easier to hit Lucio when he is skating around fast, whether he has his speed aura on or not.  Graviton Surge is another counter to Lucio's fast movement as it can be tough to avoid a Graviton Surge since it get activated so quickly.  However, when trapped in a surge, Lucio can use his ultimate Sound Barrier to protect his team from AOE damage.

When Lucio uses his ultimate Sound Barrier, his team may think they are invulnerable and will go right up in the front lines to do some massive attacks for a brief period of time.  This is a great moment to capitalize on this to use a Particle/Projected Barriers to soak up as much damage as possible, then quickly back off.  If your Particle Barrier is still on a cooldown, just take cover in the meantime until Sound Barrier fades out.

Zenyatta:  Zarya is a great counter to Zenyatta because her barriers will remove Zenyatta's Orb of Discord from her or from her allies.  Although, Zarya is one of the slowest heroes to reach getting behind a wall to block Zenyatta's line of sight to remove the orb.

Zarya's alternate fire (charged particle shots) are deadly against Zenyatta's slow movement as the AOE splash damage will be harder for Zenyatta to dodge.

Zenyatta can counter Zarya's Graviton Surge with his ultimate Transcendence, which will save him and rapidly heal his trapped allies from damage.

Soldier 76:  Soldier 76's Pulse Rifle will be a nuisance to deal with as it does a good amount of damage.  If you can, try to get close to him and use your short range beam on him, he will become weaker to you close up, especially if your Particle Cannon is charged up.  Particle Barriers are great for blocking Soldier 76's Helix Rockets from hitting you and to protect your allies behind you as well.

Soldier 76 is usually in range to be targeted by Graviton Surge, as he typically stays with his team while putting down Biotic Fields to heal them so he is usually in the right spot for a Graviton Surge most of the time.  There is not much Soldier 76 can do to counter a Graviton Surge besides putting down a Biotic Field to keep his allies healed a bit.  However, Soldier 76's Sprint ability does enable him to reposition himself in different spots quickly away from Zarya to potentially avoid Graviton Surge and her short range particle beam.

Soldier 76's ultimate Tactical Visor is generally not good to use on tanks, but Zarya is the most prone tank target for Tactical Visor since she has poor mobility and lacks the most with blocking, healing or HP of any tank.  If targeted by Tactical Visor, just use a Particle Barrier and take cover if you can.

D.va:  Zarya's explosive particle charges are very deadly to D.va from medium to long range, since D.va is such a big target and moves slow when firing.  Close up and D.va can dish out more damage to Zarya with Fusion Cannons (as long as Zarya's gun is not charged up).

D.va's Defense Matrix does block Charged Particle Shots and even Graviton Surge (before it deploys).  Defense Matrix does NOT block Zarya's short range particle beam.

Zarya's poor mobility makes running away from D.va a challenge, but you can use a Particle Barrier to stay alive longer.  Particle Barriers can also save Zarya from D.va's ultimate Self-Destruct while still being able to continue attacking at the same time.

Zarya's ultimate Graviton Surge is not very effective against D.va.  If trapped in the surge, D.va can use a Defense Matrix to block incoming shots and projectiles from hitting her trapped allies.  D.va can also use her Boosters to escape out of it as well.

D.va can also use a Defense Matrix to absorb Zarya's Graviton Surge before it detonates, but one would need to be extremely quick with the trigger in order to stop it.  This also means don't use Graviton Surge at a Defense Matrix or it will get destroyed.

Symmetra:  Both heroes are not much of a threat to each other.  Symmetra is usually off in the distance putting up Sentry Turrets or lobbing Photon Orbs and is usually far enough away to avoid Zarya's short range particle beam, although Symmetra is somewhat susceptible to Zarya's explosive charge shots from a distance.

Symmetra's Photon Orbs will still strike through Zarya's Particle Barriers, but the barrier will absorb the damage making Zarya's gun stronger.  One fully charged Orb will give Zarya +40 power for her Particle Cannon.  And since Photon Orbs fly so slowly, you can purposely run into them while having a Particle Barrier on to absorb the damage to enhance your Particle Cannon.

If Zarya walks in a room full of Symmetra's Sentry Turrets, she can easily take them out with the AOE damage of her explosive charge shots, or even her short range beam while protecting herself with a Particle Barrier.  Sentry Turrets will still attack targets that have Zarya's barrier on.  The barriers will absorb the damage to make Zarya's weapon stronger and not slow down the hero with the barrier.

Symmetra's Teleporter ultimate is safe from Zarya due to the fact that Zarya has very poor mobility and is generally not a Teleporter hunter.

Symmetra is a sitting duck to Graviton Surge, as there is nothing she can do to escape or protect herself while she is trapped in the surge.

McCree:  Zarya's Particle/Projected Barriers help protect you and your allies from McCree's flashbangs and fan fire attacks.  However, Zarya's barrier only lasts for a very short period of time, leaving her vulnerable to McCree most of the time.  Overall, Zarya's Particle/Projected Barriers, health, and damage from her particle gun will give McCree a tough time.

Out of all the tanks, Zarya is the weakest to McCree's ultimate Deadeye.  Her lack of mobility to take cover and lack of damage mitigation to protect her whole team makes Zarya and her allies more vulnerable to Deadeye overall.

Graviton Surge is very deadly to McCree as he is usually right in the targetable spot for it along with not having ways to escape or counter it.

Pharah:  Pharah pretty much pwns Zarya.  It's hard to hit enemies far away or up in the air with Zarya's Particle Cannon, as explosive charges won't be able to do their AOE damage to hit Pharah while she is flying and hovering around in the air, this makes damaging Pharah extremely difficult for Zarya.

Be careful when Pharah spams her rockets down at you, try to take cover under a ceiling/wall or turn on your Particle Barrier to block and absorb all the rocket damage.  Keep an eye out where Pharah is firing her rockets at, and use a Projected Barrier on an ally that is being attacked by her.

Since Pharah is usually in the air with her Jet Packs, she is usually in the clear of Graviton Surge (since it is a ground ability).  But if for some odd reason Pharah does get trapped in it, she doesn't have much to counter it besides using her Barrage ultimate (Jet packs won't get her out of it).

Pharah's ultimate Barrage can be deadly against Zarya due to her poor mobility to dodge it, but you can use a Particle Barrier to protect yourself (only for 2 seconds though).

Widowmaker:  Widowmaker's sniping abilities are very deadly to Zarya and there isn't much Zarya can do about her.  Zarya's Particle Cannon usually doesn't reach far enough to damage Widowmaker, even with her explosive charges, which Widowmaker can usually strafe to avoid or grapple to a different sniping spot.

It's also hard to guess which ally to give a Projected Barrier to against her, since her sniping can involve any ally around you.

Widowmaker is also usually safe from Zarya's ultimate Graviton Surge since she is usually away from the heart of the battle and off sniping by herself.  Widowmaker can also escape out of a Graviton Surge by grappling somewhere.

Bastion:  Watch out for Bastion Sentries, even with barriers.  While in Sentry Form, Bastion can melt Zarya's barriers (both personal and projected) in about a half a second, normally they will last for 2 seconds before the cooldown is up for it.  Even though you will receive +40 strength to make your Particle Cannon stronger, it doesn't take long for a Bastion Sentry to finish Zarya off completely before she gets many shots in.  Because of this, barriers have minimal use against Bastion's insane DPS while in sentry form.

Zarya's slow mobility in general will give you a tough time taking cover from Bastion and you will have a tough time flanking him unnoticed.

From a distance Zarya can hit a Bastion Sentry with her explosive charge shots which has the potential to do a lot of damage to him, and she can sometimes achieve this while not being in his line of sight.  This is one of the best tactics you can do against a Bastion Sentry.

Graviton Surge can be effective on a Bastion Sentry as he has no counters for it.  Bastion Sentries can still fire while stuck in a Graviton Surge, but he is still very susceptible to area effect damage by you and your teammates.

Zarya can protect herself with a Particle Barrier against Bastion's Tank form ultimate, and you can protect an ally with a Projected Barrier against Bastion's Tank Form as well.

Mercy:  Although Zarya can easily kill Mercy in combat with her explosive charge AOE shots, Mercy is deadly mostly due to her ultimate Resurrect.  Resurrect is generally very powerful as it can bring all her dead allies back to life.  Resurrect is a hard counter to Graviton Surge.  As long as Mercy doesn't get trapped in the surge or is able to survive it (such as with a Projected Barrier), she can then resurrect all the dead heroes that died from the surge.  This can make Graviton Surge very ineffective against Mercy.  Mercy can also escape out of a Graviton Surge by using her Guardian Angel ability to fly to an ally that is further away from the surge.

Junkrat:  Junkrat's mines and traps are no real threat to Zarya since she moves slow and is able to spot them before she runs over them, and even if you actually do run over them, you can quickly use your Particle Barrier to save yourself from any mine detonations.  If your is quick enough, you can save your teammates from the trap/mine combo by giving them a Particle Barrier as well.    Zarya can still get stuck in Junkrat's Trap even with a Particle Barrier on, but it will absorb the damage to make her gun stronger.

Zarya is most prone to Junkrat's grenade spam, since she doesn't have any means of healing herself besides her regenerating shield.  However, Zarya's alternate fire (explosive charges) actually tends to be quite effective on Junkrat, since it does splash damage and can hurt Junkrat hiding around an object or wall.

If you happen to trap Junkrat in a Graviton Surge there is nothing he can do to escape or counter it.  Gravition Surge will also trap Junkrat's ultimate Rip-Tire.  You can also protect yourself from Rip-Tire detonations by using a Particle Barrier, or protect an ally with from it with a Projected Barrier.

Torbjorn:  Zarya's alternate fire with explosive charges are somewhat effective against turrets thanks to the AOE splash damage, enabling it to potentially hit both the turret and Torbjorn at the same time but it isn't really enough to deal with Torbjorn's fast turret repair, unless your gun is charged up enough.

Zarya's Particle Barriers can help you and one of your allies get closer to Torbjorn's turret allowing you to take it out a bit easier.  Torbjorn's Turrets can also attack Zarya's barriers, thus wasting the turret's fire power while Zarya's barriers absorb the damage to enhance Zarya's Particle Cannon.

Graviton Surge seems to only work on Torbjorn about 50% of the time, since sometimes he places turrets away from the heart of his team, such as on high up ledges, away from Graviton Surge.  If you do happen to trap Torbjorn in a surge, there is nothing he can do to counter it.  Graviton Surge has no actual effects on turrets.

Reinhardt:  Both heroes generally keep their distance from each other, but Reinhardt can do serious damage to Zarya up close with his melee attacks and Charge ability as long as she is unable to use her Particle Barrier to protect her.  Zarya's poor mobility only makes it harder for her to escape Reinhardt's deadly melee attacks and Charge ability.  Reinhardt can still Charge Zarya while her Particle Barrier is up and Reinhardt's shield can block both of her attacks from her Particle Cannon (short range beam and explosive charges).

Zarya's Particle Barriers can block Reinhardt's Fire Strike damage and absorb the damage to make her Particle Cannon stronger.  A Fire Strike will still pass through Zarya's barrier, doing no damage to her and giving her +40 power for her Particle Cannon.

Graviton Surge is not very effective against Reinhardt, as he is one of the few heroes that can actually escape out of it by using a Charge.  Those rocket thrusters on Reinhardt's back is OP.  Although his shield will not block the surge or the initial projectile shot.

Reinahardt's ultimate Earthshatter will NOT knock Zarya down when she has her Particle Barrier up, and she will absorb the damage as well (+13 to her Particle Cannon strength).  The same thing will apply when her Projected Barrier is on an ally.

Tracer:  Tracer is a hero known for her superior flanking abilities with her quick movements and constant harassing.  Luckily, Zarya's Particle Cannon works decently on Tracer as her short range beam and AOE splash damage from the charged shots are easier to hit Tracer than most other weapons in Overwatch.  Tracer's Pulse Pistols are only mediocre at best, especially against tanks.  Zarya's Particle Barriers will make it harder for Tracer to harass and flank Zarya.  Zarya can also protect allies that are getting flanked by Tracer with Projected Barriers.

Tracer's ultimate Pulse Bomb is very deadly and is one of the hardest ultimates to counter, but Zarya's Particle Barrier is a great counter to it, as it will absorb all the damage and transfer it to her Particle Cannon to make it stronger.

Since Tracer is usually out harassing and flanking, she is usually in the clear of Graviton Surge.  However if Tracer does get trapped in Zarya's Graviton Surge, she can just use Recall to escape out of it, or use two quick Blinks as well.

Overall, Tracer is better off avoiding Zarya and focus on killing other easier targets.

Roadhog:  Zarya has fairly good counters to Roadhog's Chain Hook.  If you get chained into Roadhog, you can use a Particle Barrier while backing up to escape.  You also need to watch out if Roadhog Chain Hooks one of your allies, if he does, simply use a Projected Barrier on that ally to save em.

From afar, you can do a lot of damage to Roadhog with your explosive charge shots, and since Zarya has the smallest hitbox out of all the tanks, she will take the least amount of damage from Roadhog's Scrap Gun.  But Roadhog will still be very deadly close up with his Scrap Gun if you cannot use a Particle Barrier to protect yourself.

Roadhog's ultimate Whole Hog can be countered by using Particle Barriers, and since Roadhog will be unable to stop shooting he will most likely still connect his scrap hits with you, which will only make your gun stronger.  However, Whole Hog will still knock Zarya back while using a Particle Barrier.

Graviton Surge is very deadly to Roadhog as he is usually in the targetable area for it and has no means to escape or counter it.

Reaper:  Reaper is similar to Tracer, where he can randomly appear out of no where and start attacking you.  Up close and Reaper's shotguns are very deadly, even to Zarya.  A Particle Barrier can protect yourself for a few seconds from him, but Reaper can easily return and fire at you when your barriers are on a cooldown.  Reaper will tend to avoid you altogether as long as you stick with your team and they have your back, as Reaper works best when trying to pick off single targets.  While playing, listen carefully for his shotgun sounds and when you hear or see a Reaper attacking one of your teammates, quickly throw a Projected Barrier on that ally to save em.

Reapers are usually in the clear of Zarya's Graviton Surge, since Reaper is usually not around his team most of the time.  If Reaper does happen to get caught in a Graviton Surge, he can simply escape out of it with Wraith Form.

Reaper's ultimate Death Blossom can be deadly to Zarya if you cannot use a Particle Barrier to protect yourself from it, as Zarya's slow mobility can easily get you stuck in it.

Hanzo:  Because Hanzo is a sniper that usually fires from a distance, it will be tough for Zarya to do damage to him with your short and medium ranged weapons.  Particle Barriers will usually just force Hanzo to fire at different targets for the time being and it can be hard to predict to use a Particle Barrier against him due to the nature of his sniping abilities.

Hanzo can sometimes be in the targetable spot for Graviton Surge, although a lot of times he can climb walls and be in a different spot from the heart of his team and can be safe from Graviton Surge.  If he does get trapped in a surge, there is nothing he can do to escape or counter it.

A Particle Barrier will block and absorb Hanzo's ultimate Dragonstrike, but keep in mind that a Particle Barrier will not fully protect you from a Dragonstrike, as Dragonstrike actually does a damage over time effect, in which it can take down your Particle Barrier and then quickly eat away at your actual hitpoints.

Zarya:  Particle/Projected Barriers will block everything Ana has, including:  Ana's Biotic Rifle, Sleep Darts, Biotic Grenades and a Nano Boosted ally (Ana's ultimate).  But Particle Barriers only last for a very short period of time so Ana will still have plenty of opportunities to use her abilities against Zarya, but your barriers can shield a lot of Ana's attack attempts.

Zarya can also use a Projected Barrier on allies that use ultimates that are very prone to Ana's Sleep Darts, such as:  Pharah's Barrage, McCree's Deadeye, Reaper's Deathblossom and Roadhog's Whole Hog.

A lot of times Ana is in a targetable spot for Graviton Surge, which can be very hard for Ana to avoid sometimes as Ana has no way to escape out of it.  If Ana gets stuck in a Graviton Surge the best thing for her to do is to simply throw down a Biotic Grenade at her allies stuck in the surge and she should keep firing at them to heal them up in the surge.  Ana should be careful not to waste her ultimate Nano Boost on one of her allies stuck in the surge as the incoming splash damage may take that ally out anyways, instead Ana can Nano Boost one of her allies that is already not in the surge to have that ally help deal with Zarya's incoming attackers effectively.

Zarya:  Dealing with another Zarya comes down to who has the better reflexes with aiming and avoiding fire once the opposing Zarya uses her Particle Barriers.

Trapping an enemy Zarya in a Graviton Surge is very reasonable, but she can use a Particle Barrier to protect herself or protect an ally with a Projected Barrier from the surge.  Another backup plan for surviving a Graviton Surge is by using your own Graviton Surge back at the enemy to trap them too, so both teams will be trapped and unable to escape from each other.