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