Here is the full list of all 18 Tres-Bashers achievements.
Get the ending while spending under 50 coins
Beat the game without dying
Beat the game without the backflip
Get the ending in under 45 minutes
Get the ending with less than 10 kills
Beat the game with the bat only
Find the MIRROR relic first
Watch the cast roll (41/41 Bestiary + End)
Collect all monster bestiary pages
Find all weapons
Bash every monster
Buy every coat color
Find the ultimate weapon
Collect all relics
Find all moves
Bash 100 monsters
Bash 50 monsters
Bash 25 monsters