Here is the full list of all 14 Dandy Randy achievements.
Finish The Game.
Beat Paul Matthews.
Beat Natalia No Good.
Find the Running Shoes.
Get at least $7500 (total).
Beat The Dusk Ghost.
Find the Hookshot.
Get at least $5000 (total).
Beat Caca The Desert Monster.
Find the Hammer.
Get at least $1000 (total).
Beat Otis the Octopus.
Find the Boomerang.
Find 15 hidden coins in a single level.