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