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