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