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