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