These are unlocked by beating stages both normally and under the Par times.

Unlockable	How to unlock
Bonus Levels	Complete all Incidents.
Gym Clothes Patty	Complete all Incidents and Bonus Levels under Par times.
Hyper Drive and Hyper Drive Bonus Levels	Complete all Incidents and Bonus Levels.
Mega Blaster	Complete all Incidents.
Pixel Patty	Complete Incident 01.