Here is the full list of all 25 Pac-Man and the Ghostly Adventures 2 achievements worth 1,000 gamerscore.
Beat the high score on all Paclantis (Chapter 2) levels.
Stun 100 enemies with Fire Pac's Special attack.
Attract and chomp 100 enemies using Metal Pac's magnet tongue.
Beat the high score on all Space (Chapter 3) levels.
Freeze 100 enemies with Ice Pac's Special attack.
Beat the high score on all Prehistoric Pac-World (Chapter 4) levels.
Beat the high score on all Netherworld (Chapter 5) levels.
Successfully complete all Betrayus Challenges at least once.
Get the Pac Prize score bonus at least once on every level.
Win a Gold Medal on every level.
Visit every Arcade Zone in the game.
Beat the high score on all Pacopolis (Chapter 1) levels.
End a level with six Health (Hearts).
Complete the Tutorial and all of the Berry Challenges.
Complete any Cyli Hover Board level without losing a life.
Complete any Spiral Cherry Copter level without losing a life.
Chomp every container in any level.
Complete the Lemon Rocket level without losing a life.
Stun 100 enemies with Rubber Pac's Special attack.
Defeat 200 Blue (Scared) Ghosts.
Defeat 5 Stone Monsters as Granite Ball Pac.
Read the bios for each of Pac's friends between levels.
Get the number of Pac's Lives up to 50.
Grab 200 Pac Pellets in a single level.
Talk to each of Pac's friends between levels at least once.