Here is the full list of all 11 Power Stealers achievements.
Defeat the Pterodactyl boss
Defeat the Gigant Robot Skeleton
Defeat the supreme Chaman Osfird
Defeat the Ultimate Weapon
Defeat the Mainframe boss
Defeat the game with only three continues or less
Defeat the game without the aid of the ShenBot
Defeat the Mutant worm on the road