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