What can heroes be commended for?

overwatch

Redditor SpriteGuy_000 has done some extensive testing, and according to his spreadsheet these are the things you can be commended for.

All Heroes

Eliminations (% Kill Participation)
Objective Time
Damage Done (% of Team Damage)
Gold Medals Earned (Total Medals)
Total Medals
Objective Kills (Eliminations)
Best Kill Streak (Eliminations)
Teleporter Pads Destroyed (Enemy Teleporters Placed)
MVP (% of Match on Fire)
Melee Final Blows (% of Final Blows)
Environmental Kills (Eliminations)
Solo Kills (Eliminations)

Bastion

Recon Kills (Eliminations)

D.Va

Mechs Called (Mech Deaths)

Genji

Damage Reflected (Deflection Eliminations)
Dragonblade Kills (Dragonblades)

Hanzo

Doesn't appear to have any unique commendations

Junkrat

Players Trapped

Lúcio

Healing Done (% of Team Damage Taken)
Sound Barriers Provided (Sound Barrier Casts)

McCree

Fan the Hammer Kills (Total Eliminations)

Mei

Enemies Frozen (Total Time Frozen)
Damage Blocked

Mercy

Players Resurrected (% of total deaths)
Healing Done (% of Team Damage Taken)
Defensive Assists (% Kill Participation)

Pharah

Rocket Direct Hits (% of Rockets Fired)
Barrage Kills (Rocket Barrages)

Reaper

Souls Consumed ()
Death Blossom Kills (Eliminations)

Reinhardt

Damage Blocked

Roadhog

Self Healing (% of Damage Taken)
Enemies Hooked (% Hook Accuracy)

Soldier: 76

Helix Rockets Kills (Eliminations)

Symmetra

Players Teleported (% Teleporter Uptime)
Sentry Turret Kills (Eliminations)
Shields Provided (% Shield Uptime)

Torbjörn

Armor Packs Created (% Armor Uptime)
Turret Kills (% Kill Participation)

Tracer

Health Recovered (Recalls Used)

Widowmaker

Infra-Sight Uptime (Recon Assists)

Winston

Damage Blocked
Jump Pack Kills

Zarya

Projected Barriers Applied (Damage Blocked)

Zenyatta

Transcendence Healing (Healing Done)
Healing Done (% of Team Damage Taken)
Defensive Assists (% Kill Participation)

Without any official data published anywhere that I can see, I can only speculate on my answer, using personal experience from both the closed and open beta, as well as many games played the last two days.

Essentially, from what I can tell, it seems that every character has the opportunity to get a few "core" commendations that are common among all of them. These likely include Eliminations, Solo Kills (questionable, see below), MVP, and Damage Done. I'm not sure if anyone has played every hero enough to confirm that any of the general commendations are impossible to achieve on a particular character, but just harder to do so among a group of 12 players (Solo Kills on Lucio for example. Not to imply that Lucio is difficult to get kills with).

Additionally, for each character, it seems there are commendations for each of their unique mechanics, include their Ultimate. Enemies Frozen for Mei, or Rocket Direct Hits for Pharah, for example.

Lastly, there are a few commendations that are limited to a character's ability to perform them. Characters that cannot move other characters should not get Environmental Kills, just as characters that cannot produce a barrier cannot get Damage Blocked. (Note that Zarya's ability to produce a Barrier would likely result in her getting a commendation for Projected Shield uses rather than the more general Damage Blocked). In a similar vein to these abilities are those that are limited to a character's role. I am unsure if Solo Kills falls into this category for Offense heroes, and right now that limits Damage Blocked to Tank heroes (unless I am forgetting someone).

Again, this is based on my experience, and I cannot find any definite rulings. Such data would be hard to find this early into the game without definite word from Blizzard.