Here is the full list of all 35 Fall Guys: Ultimate Knockout trophies - there are 21 bronze, 8 silver, 5 gold and 1 platinum.
Win 20 Episodes
Get first place in a racing round 5 times
Reach lvl 40 fame during a season
Win 7 Episodes
Win an Episode with a custom Punchline equipped
Reach lvl 25 fame during a season
Equip a legendary Body Colour, Pattern, Upper and Lower Costume piece
Get first place in a racing round
Qualify from 100 rounds
Fall for at least 3 seconds before landing on your head
Knock someone over
Bump into 3 people while rolling on the ground before getting up
Reach terminal velocity
Equip your first cosmetic item
Equip an uncommon or better Body Colour, Pattern, Upper and Lower Costume piece
Equip your first legendary customization item
Qualify from a round without falling over even once
Bump into other Fall Guys 1000 times in total
Reach lvl 10 fame during a season
Win your first Episode
Qualify after a round goes to overtime
Share a hug with a Fall Guy
Equip a rare or legendary Body Colour, Pattern, Upper and Lower Costume piece
Qualify from your first round
Qualify from a racing round despite falling over more than 10 times
Clock up 1 hour total time falling
Acquire all other trophies
Unlock 50 cosmetic items from the store
Unlock 10 cosmetic items from the store
Get first place in a racing round 20 times
Win 5 Episodes in a row
Qualify from 500 rounds
Win an Episode as part of a party of 3 or more players
Qualify from a team game with a score of 1
Perform an emote just before coming first in a race round