Here is the full list of all 20 Rainbows, toilets & unicorns! achievements.
Flat Earth Defeated!
No Vax Defeated!
Nuclear Guy Defeated!
Macho Man Defeated!
Kill 450 Enemies in a Run
Donut Man Defeated!
Long Ears Defeated!
Salt Man Defeated!
Influencer Defeated!
Streamer Defeated!
Use Shields 10 Times
Use Magnet 10 Times
Use Rainbow 10 Times
Spoiled Child Defeated!
Use Double Shot 10 Times
Gold Boss Defeated!
Flying Carpet Defeated!
Tanned Toupee Defeated!
Vegan Defeated!
Nikky Mouse Defeated!