Here is the full list of all 50 Ultra Savage achievements.
Defeat Unlimited Nightmare Error
Enhanced Item +20
Reach Level 200
Defeat Dr. Congo
Defeat Unlimited Error
Defeat Error
Defeat Oreb and Zeeb
Have Over 10'000'000 HP
Defeat Githeon The Galactic Conqueror
Reach Level 180
Deal Over 10'000'000 Damage
Reach Level 160
Defeat Xoreb
Made A Costume
Reach Level 140
Do Ten Time Travels
Have Over 1'000'000 HP
Defeat Nahash
Enhanced Item +10
Deal Over 1'000'000 Damage
Do Six Time Travels
Defeat King Bera the Reaper
Reach Level 100
Defeat Lord Pretty Face Coolinagi
Enhanced Item +6
Enhanced Item +3
Have Over 100,000 HP
Have Over 50% CRIT
Have Over 100 CHI
Do Your Second Time Travel
Reach Level 80
Have Over 300% ATK SPD
Defeat Raki-Raki The Demolisher
Maxed Out A Skill
Deal Over 100'000 Damage
Defeat Liki Lee The Amgi-Turner
Reach Level 60
Deal Over 9'000 Damage
Do Your First Time Travel
Defeat Heli Boss
Deal Over 1'00 Damage
Reach Fusion Level 10
Reach Level 30
Have Over 150% ATK SPD
Defeat Prince of Madness
First Enhancement
Reach Level 10
Equip a blade and meet Kairon
Do your first fusion
Have over 3'00 HP