Reaper:  The idea is to keep Reaper away from you in close range and all of Lucio's abilities will allow you to do just that.  Speed aura helps you and your team to run away from Reaper's deadly close up shotguns.  Lucio's Soundwave (alternate fire) can knock back approaching Reapers.  Sound Barrier can be used to save your whole team from Reaper's Death Blossom (ultimate).

Winston:  In order for Winston to do damage to anyone, he needs to get in close range in order to do damage with his Tesla Cannon or his ultimate Primal Rage.  Like with Reaper, Lucio has multiple ways to stay away from Winston's close up attacks.  Lucio can use his speed aura to move away from Winston while still being able to fire his sonic projectiles at him.  However, Winston's Barrier Projectors do a great job at blocking Lucio's sonic projectiles.  Up close and Lucio can use his Soundwave ability to knock Winston back, which can make it hard for Winston to deal damage with his Tesla Cannon or Primal Rage ultimate.

Lucio can also use his ultimate Sound Barrier to save him and his whole team from Primal Rage, which is one of the hardest counters to it.

Genji:  Lucio's speed and heal auras work nicely against Genji's shurikens.  Speed aura will make it much harder for Genji to land shurikens on you and your team plus your heal aura can heal up any shuriken damage done.

Even though Lucio's sonic projectiles can be deflected by Genji's Deflect ability, it's not very effective against Lucio because of how slow the projectiles move and how fast Lucio can move to avoid it.

Genji's Swift Strikes can be hard to avoid sometimes but remember you can use Soundwave to knock him back and if he approaches you, consider turning on speed aura to make it harder for him to Swift Strike you.

Lucio and his team can easily avoid Genji's Dragonblade with a quick drop the beat (Sound Barrier).  If Sound Barrier is not available, then speed aura with an Amp it Up is the next best thing to use.  Soundwave is also useful against Dragonblade as well.

Mei:  Mei's freeze gun up close can be devastating, but luckily Lucio can use Soundwave to knock her away from him, which will give you enough time to move away from her freeze gun.  Sound Barrier can also be used to save allies from getting frozen by Mei's freeze gun.  Mei's long range icicle shots are not too much of a problem for Lucio thanks to his faster movement speed, especially when speed aura is on.

Mei's Ice Wall doesn't effect Lucio too much since he can use his speed aura with Amp It Up to quickly navigate around it.

Lucio can save his team from Mei's Blizzard with his speed aura combined with his Amp it Up ability.  And he can further protect his team from Blizzard with Sound Barrier as well.

Roadhog:  It's generally hard for Roadhog to Chain Hook Lucio due to his overall fast mobility, especially when speed aura is on, this also makes chain hooking Lucio's allies a difficult task as well.  If you actually do get chain hooked in, Lucio can use Soundwave to knock back Roadhog to avoid further damage.  You can then use speed aura with an Amp It Up to quickly run away.  Alternatively you can use Sound Barrier to save yourself as well.  Sound Barrier can also be used to save an ally that just got chained in by Roadhog.

Sonic projectiles are very efficient to use against Roadhog due to his large hitbox and slow mobility.  This will help you rev up your ultimate faster.

Roadhog's ultimate Whole Hog can be countered by Lucio's Sound Barrier, if it's available.  Alternatively you can use a Soundwave if you are close enough.

Pharah:  Pharah is a threat to Lucio mostly due to the fact that Pharah flies and hovers around in the air most of the time while launching rockets down at Lucio and there is not much he can do about it.  Lucio's only way of damaging Pharah is with sonic projectiles, which are simply not fast enough to aim well at her.  It will take a bit of practice to shoot Pharah down with sonic projectiles.

However, Sound Barrier is a strong counter to Pharah's ultimate Barrage.

Zarya:  Try to keep your distance from Zarya because her short range particle beam does more damage than her longer ranged charged shots.  You can use Soundwave to help keep her away from you.  However, because her longer ranged charged particle shots do AOE splash damage, she will have an easier time doing damage to you and your team even when your speed aura is on.

When dealing with Zarya you need to watch out for when she uses a Particle Barrier on herself or a Projected Barrier on one of her allies.  If you shoot at them, the barriers will block and absorb the damage, then convert the damage to enhance her Particle Cannon.  So be careful with your sonic projectile spam when the enemy has a Zarya on their team and avoid firing at her barriers.

Zarya's ultimate 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.

Ana:  Ana's Biotic Grenades are a huge threat to Lucio and his heal aura.  When used, Biotic Grenades will prevent all healing on Lucio's allies struck by the grenade and Lucio himself as well.  The best time for Ana to use a Biotic Grenade is right when Lucio uses his Amp It Up ability.  This will totally disable any rapid healing amongst any ally struck by the grenade.  The main way for Lucio to counter a Biotic Grenade is to switch to speed aura to allow any severely injured allies to run away for cover instead.  Please note that Ana's Biotic Grenades have no effect against Sound Barrier.  If you were struck by a Biotic Grenade while having heal aura on, your allies can still receive the healing benefits of heal aura as long as they didn't get struck by the Biotic Grenade as well.

Ana's Sleep Darts are not too useful against Lucio.  Sleep Darts are generally difficult to aim at Lucio and his overall fast movement.  Even if she does hit Lucio with a Sleep Dart, his auras will still be active on himself and his team.  If Ana hits one of Lucio's teammates with a Sleep Dart, Lucio can activate Sound Barrier to awaken the sleeping ally.

Sound Barrier is a good counter to Ana's ultimate Nano Boost.  A Nano Boosted enemy will have virtually no hope of killing someone with a Sound Barrier protection on them.  Although Nano Boost lasts a few seconds longer than Sound Barrier, so it still has a chance to do some damage to your team.  Also Ana's Biotic Grenades do NOT prevent Sound Barriers.

Mercy:  Lucio and Mercy rarely interact with each other during matches due to their support roles in the backlines.  Both heroes have similar roles to support and heal allies, however Mercy does a better job at healing single heroes with her Caduceus Staff than Lucio's heal aura.  This could allow Mercy to have a tankier hero to fight up against Lucio's team.  However unlike Mercy, Lucio is able to heal all his teammates while at the same time fire his weapon.  Both Lucio and Mercy has their ups and downs as support and overall this isn't a real 1on1 matchup to consider as they both rely on their team to directly support them back.

As far as self defense goes for 1on1 battles, Lucio does a much better job at soloing enemies than Mercy thanks to his self heal and Sound Barrier ultimate.  Mercy pretty much relies on at least one ally to protect her.

Soldier 76:  Soldier 76's Biotic Fields healing ability is a good counter to Lucio's sonic projectile spam and since both heroes tend to stay a distance form each other your Soundwave ability will rarely get used against Soldier 76.  Lucio's speed aura will definitely make it harder for Soldier 76 to aim his Pulse rifle and Helix Rockets at you or your teammates.

Soldier 76's ultimate Tactical Visor can easily be canceled out with Lucio's Sound Barrier.  If Sound Barrier is not available, then your next best thing to do is switch to speed aura with an Amp It Up to allow you and your teammates to run and take cover from it.

McCree:  Do not get close to McCree or he can easily Flashbang and then Fan Fire you down easily.  Luckily, Lucio does a good job of keeping a distance from enemies thanks to his Soundwave knock back and fast movement aura, which will especially come in handy for running up against McCree.  You should also consider using a Sound Barrier against McCree if you get too close to him, as it will only take one good Flashbang and fan fire to take Lucio out.  Sound Barrier can also be used to save an ally who just got flashbanged by a McCree as well.

McCree's ultimate Deadeye can be countered by Lucio's Sound Barrier.  If Sound Barrier is still on a cooldown, then use speed aura with Amp It Up to allow you and your team to run and take cover from it.

Tracer:  Dealing with Tracer can be very annoying as her fast movement with blinks can be tough for Lucio to aim his sonic projectiles at her.  Since Tracer generally needs to get in close range to do her damage, you can use Soundwave to knock her away from you, and your heal aura can easily patch up any damage done by her Pulse Pistols.

Tracer's ultimate Pulse Bomb can be countered by Sound Barrier.  Once Tracer throws out a Pulse Bomb it does 400 damage after 2 seconds, so you have a short window of opportunity to save yourself by quickly using Sound Barrier.  If you are quick enough, you can also use Sound Barrier to save an ally from Tracer's Pulse Bomb as well.  If Sound Barrier is not available to you, then just expect to die as long as Tracer stuck the bomb on you.  If the bomb is not actually stuck on you, then you can try to escape it by switching to speed aura with an Amp It Up.

Overall the fight is somewhat even and they will both have troubles taking each other out.

Junkrat:  Lucio's heal aura is a powerful counter to Junkrat's grenade spam, but your speed aura can get you and your teammates trapped easier by Junkrats Trap/Mine combo, since faster movement makes it harder to dodge traps before running over them.  Because of this, a smart Lucio player will use his heal aura more often than speed when facing an enemy Junkrat.  Although, Junkrat's ultimate Rip-Tire can force Lucio to use his speed aura to escape from the tire explosion, which could potentially make your team run into his traps easier.

Rip-Tires can best be countered by Lucio's Sound Barrier ultimate as long as Junkrat detonates the tire while your team still has high shields.  It's also best to be on the safe side and use speed aura with an Amp It Up to allow you and your allies to run from the deadly tire as well.

Bastion:  It doesn't happen too often, but Lucio can use his fast speed boost and wall skate abilities to get around behind a Bastion to flank him.  Doing so can put Lucio's team more vulnerable because he is not there healing his team and is taking a risk to flank Bastion, that's why it's rare to see this.

Sound Barrier is a useful tool for allowing your team to push towards a strong Bastion defense, but Lucio can go down relatively quick to Bastion's gatling gun once the shield wears off thus making this a more even fight overall.

Bastion's ultimate Tank Form can also be counter by Sound Barrier, rendering Tank Form virtually useless for the duration of his Lucio's ultimate.  However Tank Form lasts 10 seconds where as Sound Barrier only lasts 6 seconds, thus giving Bastion a slight edge in this case as long as Lucio doesn't kill Bastion during Sound Barrier.

Widowmaker:  Since Lucio is a strong support hero with incredible healing abilities, he is a prime target for Widowmaker to snipe.  Lucio's fast movement ability makes it somewhat harder for Widowmaker to snipe him as he is skating around, especially when he has his speed aura on.  However, when Lucio uses his heal aura he will be a much easier target for Widowmaker to snipe.

Since Widowmaker is usually much further than Lucio, she doesn't need to worry too much about Lucio's Sonic projectiles as she can simply strafe to avoid it, or grapple to a different sniping spot.

Watch out for Widowmaker's Venom Mines as sometimes she will place them on Payloads, or sometimes even underneath Payloads.  Keep an eye out for them and avoid running into them.  Remember you can attack and destroy Venom Mines.

When you hear Widowmaker use her ultimate Infra-Sight which allows her and her allies to see enemies through walls, consider using Sound Barrier to counter it.

D.va:  Remember that D.va will do the most damage to you up close.  So if she comes near you, just use a Soundwave on her to knock her away from you.  Also consider speeding away from her to keep your distance from her deadly up close Fusion Cannons.

D.va's Defense Matrix ability will block your sonic projectiles, but it will not block your Soundwave ability.

Sound Barrier will not be enough to totally block off D.va's ultimate Self-Destruct, however allied tanks receiving Sound Barrier may just have enough health to survive a close up Self-Destruct hit.  Lucio's Sound Barrier provides his nearby allies with +500 shields, while D.va's Self-Destruct does up to 1000 damage to all nearby enemies.  Because of this, you should also turn speed aura on with an Amp It Up to really make sure you and your allies can take cover from the Self-Destruct explosion quick enough.

Hanzo:  Lucio's amplified movement speed is devastating to Hanzo.  Hanzo already has a tough time aiming at his enemies with his bow, imagine all his enemies with much faster movement, it becomes so much harder to aim bow shots.  So when facing a Hanzo, consider using speed aura as often as you can.  Speed aura will also help you and your team to dodge Hanzo's ultimate Dragonstrike easier.

You still need to watch out for Hanzo because Lucio is a prime target for him to take down.  Keep him in your sights and try to make yourself a harder target to hit with his bow by switching back and forth from healing to speed.  If you get close to Hanzo, keep jumping to increase the chances to avoid being hit by his Scatter Arrow shots.

Lucio:  When versus another Lucio, both Lucios will be a prime target to each other as it's important to take the healer out first if possible.  This means you and your team will need to work together to take out the opposing Lucio.  Strategies can differ depending on what allies you have but generally you will want to focus fire on the enemy Lucio as much as possible while focus on using the correct auras to buff your team in the meantime.

Torbjorn:  Lucio is only a minor threat to Torbjorn.  Lucio's Sonic Amplifier weapon is not very effective against Torbjorn since they are usually a distance from each other and Torbjorn will have time to dodge the sonic projectiles (while repairing his turret) and will be well out of range of Lucio's Soundwave (alternate fire) most of the time.

Sound Barrier can be very powerful against Torbjorn and his turret since it will allow your team to be temporarily powerful enough to absorb turret damage for a number of seconds, allowing your team to push toward Torbjorn's turret to take it out.  Along with Sound Barrier, you can also use speed aura combined with an Amp it Up to quickly get your entire team closer to Torbjorn's turret to effectively take it out.  This same strategy happens to also be effective at taking out Torbjorn when he uses his ultimate Molten Core.

Reinhardt:  It's important to keep Reinhardt out of melee range, as that is where Reinhardt will do most of his damage at.  In close range, Reinhardt's melee swings with his Rocket Hammer are very deadly and it will be easier for him to Charge you in close quarters.

Soundwave is vital to use on Reinhardt to further keep him away from you.  But Reinhardt's shield will block Soundwave, unless you go through his shield a bit and then trigger Soundwave. You should also consider using speed aura with an Amp It Up to allow you and your team to keep a distance from Reinhardt in general.  Soundwave does work on Reinhardt's Charge, but it will only bump him a bit, it won't stop it completely.

Reinhardt will have a difficult time aiming Fire Strikes or Charges on Lucio or your allies if you have speed aura on.  And even when it's not on, Lucio still has the fastest basic ground movement speed compared to any of the other heroes in Overwatch, thus aiming attacks at Lucio can be quite difficult for Reinhardt.

Up close and Reinhardt may use his ultimate Earthshatter, which can be devastating.  If you can, use Sound Barrier immediately to save you and your allies from any further damage.

Zenyatta:  Zenyatta's basic attack weapon (Orb of Destruction) is actually quite powerful, however it will be much harder for Zenyatta to aim his energy orbs at fast moving targets with speed aura.  Since Lucio has the fastest ground speed (even without speed aura) it will be harder for Zenyatta to aim his energy orbs at you, and especially his charged volley orb shot.  On the other hand, it will be a bit easier for Lucio to hit Zenyatta with sonic projectiles since Zenyatta is a much slower moving hero.

If Zenyatta puts his Orb of Discord on you, take things safer by not going in the front lines as much, stay in the back and support your team while spamming sonic projectiles.  Basically, make it harder for your enemies to hit you, this will in turn waste Zenyatta's Orb of Discord.  If you want to remove the Discord Orb, then a speed aura combined with an Amp It Up allows you and all nearby allies to quickly go behind a wall to remove the orb.  Lucio's ultimate Sound Barrier will also negate a lot of damage done by the Discord Orb to whoever has it and got the sound barrier.

Zenyatta's ultimate Transcendence works similar to Sound Barrier in which both ultimates provides nearby allies with extra health to withstand more damage.  With this in mind, consider backing off away from Transcendence for it's duration or use a Sound Barrier to counter it back.

Symmetra:  Both Symmetra and Lucio generally keep a distance from each other while spamming each other with projectiles.  Symmetra usually lobs photon orbs which are not too hard to dodge since they move so slow, but photon orbs can strike through and damage all targets in its path.  Lucio's fast movement makes it really easy to dodge these orbs.

If Symmetra gets to close to you, she can do some decent damage with her short-range photon beam.  In this case, just use Soundwave on her to knock her away from you, while backing away from her and you should be fine.

When running into a room full of Symmetra's Sentry Turrets, it's wise to quickly turn on your heal aura with an Amp It Up while taking out the turrets with sonic projectiles.  As a last resort, Sound Barrier can be used if you need extra shielding from her turrets.

Lucio is generally not a Teleporter hunter, but Lucio can go hunt down a Teleporter if he needs to with his speed aura combined with an Amp It Up.  It can be risky though, I would make sure you have a Sound Barrier on hand to escape out of deadly situations if you need to.