Here is the full list of all 43 Override: Mech City Brawl achievements.
Win 5 online matches in a shared-mech
Win your first online match with any mech
Win an online match without using your Ultimate ability
Win an online match without using any items
Equip your first accessory
Complete the tutorial
Win 50 online matches
Win an online match on every map
Win an online match with each of the 12 starting mechs
Win 5 online matches with each of the 12 starting mechs
Win an online match with an ultimate attack as the final blow
Win an online match without using any special abilities
Unlock 30 accessories
Unlock your first random legendary skin
Unlock an epic skin for each of the 12 starting mechs
Unlock a total of 100 skins and accessories
Unlock all skins for a mech
Unlock the "Infected" skin for all 12 starting mechs
Get recruited by General Mavis
Met Malika in the campaign
Defeat the Shaman Xenotype boss
Defeat the Muscle Xenotype boss
Defeat Malika's mech in the campaign
Defeat the Flying-Shrimp Xenotype boss
Travel to the Moon in the campaign
Beat the campaign
Beat the campaign as Setesh
Defeat 25 Xenotypes
Defeat 500 Xenotypes
Execute 10 Counter-Attacks
Execute 50 Counter-Attacks
Knock down 3 mechs with Cocada's wind ability in an online match
In an online match, avoided 2 attacks with Mya's substitution ability without taking damage in between
Use MetaGeckon's rolling ability 30 times in online matches
Absorb a total of 1000 damage with Setesh's pyramid ability in online matches
As Vidar, trap enemies 4 times in a single online match
In an online match, use Contessa's cursed hand ability to stop an incoming dive kick
In an online match, use Vintage's teleport and get caught in an enemy's ultimate
Throw Crystal's hammer to finish off a frozen opponent in an online match
In an online match, use Rocca's rocket punch to hit an enemy twice in a single attack
In an online match, use Shifu's ultimate on a blocking opponent
Using Watchbot, win an online 1v1 match in Japan without losing health
Hit a total of 10 enemies with Pescado's ultimate chair shot in online matches