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