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