There are 12 Trophies that can be collected.

Bronze

The First Dance    
Danced through Regular mode!     

Let's Dance Together!    
Danced through Team High Score with 2 players!     

Strike a Pose    
Danced through Freeze & Shake!     

The Modern Mixtape    
Created 'Your Playlist' in Playlist mode!     

First Playlist Completed!    
Danced through 1 preset Playlist in Playlist mode!     

Mixing Things Up    
Danced through 1 Medley!     

Are You Forming a Dance Crew?    
Danced through songs in Team High Score 50 times in multiplayer!     

You're a Poser    
Danced through songs in Freeze & Shake 50 times!

Silver

Medley Master    
Danced through 50 Medleys (outside Non-Stop Shuffle)!     

Movin' on up!    
Danced through songs in Regular mode 50 times!     

Impressive Score!    
Earned 12,000 or more points in any song in Regular mode!

Gold

Just Dance Virtuoso    
Earned at least 12,000 points in all songs in Regular mode!

http://www.ps3trophies.org/game/just-dance-kids-2/trophies/