Here is the full list of all 75 Guts And Goals achievements.
Unlock this character
Unlock a mutator
Unlock a minigame
Unlock a weapon
Unlock a skin
Unlock all mutators
Unlock all minigames
Unlock all weapons
Unlock all skins
Unlock all characters
Unlock all stadiums
Unlock all secrets
Unlock the stadium
Unlock the minigame
Discover the secret