Here is the full list of all 16 Xtreme Paddleball achievements.
Hit the ball five times in a row
Defeat every fan in a level
Get killed by a fan
Stand on the desk
Hit the ball ten times in a row
Sit through the credits
Get 500 hits without firing a shot
Spend five minutes in the shooter level after finding the dossier
Complete the mine level
Use the teleporter
While invincible, get hit by an enemy
Complete the shooter level without dying
Complete the mine level without dying
Shoot a fan that didn't see you