Here is the full list of all 20 YUKI achievements.
Reach Elite Space Ranger without any power-ups.
Completed the game with Swarm Bizarre
Reach Elite Space Ranger without any health bits.
Reach Elite Space Ranger without killing any Yokalien.
Reach Elite Space Ranger on Insane Level.
Kill 1500 Yokaliens in Endless Mode.
Reach Space Lieutenant on Standard Level.
Completed the game with Sonic Slasher
Completed the game with X-Ploder
Completed the game with K1-M1
Play 7 minutes of Endless Mode in 1 run.
Reach Space Commander on Expert Level.
Finished Episode 6
Completed the game with Tracking Star
Finished Episode 5
Finished Episode 4
Finished Episode 3
Finished Episode 2
Finished Episode 1
Completed the intro level