Here is the full list of all 50 Knockout City achievements.
Complete 30 Crew Contracts
Complete 100 Contracts
In Back Alley Brawl, Avoid a thrown dodgeball by entering a Tube
Win a match while having a Legendary Outfit equipped
Win matches with 10 unique Outfits
Score 100 KO Finishes with Ultimate Throws
Use 5 Energy Drinks
Catch 1000 dodgeballs
Win a match while having an Uncommon (or rarer) accessory equipped in each slot
Play 100 matches
Complete 5 Season Contracts
Earn 100,000 XP
Score 1000 KOs
In Knockout Roundabout, KO Finish an opponent while riding a car
Win 10 rounds with five times the opponent's score
Earn 50,000 XP
Win 30 matches
Win a match without being KO'd
Catch a Sniper Shot
Play 30 matches while grouped with a Friend
In Rooftop Rumble, glide from the Bandstand to the Gardens
KO two opponents with a single Bomb ball
Throw a Caged player off the map
Win 10 matches while grouped with a Friend
Be the MVP of a three or four player team 5 times
Score 10 KOs without being KO'd
Complete 5 Event Contracts
Score 3 Hits with a Multi Ball in quick succession
In the Hideout, tackle the T.A.R.G.E.T. Dummy off the roof
Win 5 matches while grouped with a Crewmate
Earn 250,000 XP
Score 1000 KO Assists
Travel 100km in ballform
Win a match without throwing a single dodgeball - Passing is allowed!
Win matches with each Style of an Outfit
Win a match while having 5 or more Legendary accessories equipped
Win matches with 20 Outfit and/or Glove Styles
Win a match while having Legendary Glasses equipped
Win a match while having Legendary Gloves equipped
Win a match while having a Legendary Glider equipped
Complete 100 Daily Contracts
Complete the first 5 Training Levels
Be airborne for 30 seconds straight while holding a Moon Ball
In Rooftop Rumble, KO Finish 3 players without leaving the bridge
In Concussion Yard, KO Finish an opponent while riding the Wrecking Ball
In Galaxy Burger, KO Finish an opponent with a trash chute
In Concussion Yard, ride the wrecking ball for 15 seconds straight
In Knockout Roundabout, ride a car all the way around
In Galaxy Burger, fall through a trash chute
In Back Alley Brawl, throw a ticking Bomb Ball into a Tube