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