Level Skip
During gameplay press Z, R, L and A simultaneously to skip to the next stage.

Hidden Character Select
At Puzzle Mode Select screen press Left, Left, Up, Down, L, R, L, R, L+R. This will bring up a Character Select screen where you can choose between the two dino's as well as some bosses.

Another Puzzle World
At the Main Menu press L, Up, R, Down. When done correctly a tiny character will appear in the lower right corner. Select Start Game now and when you select Puzzle Mode it will say Another Wolrd.

Hidden Characters In Vs. Mode
Do the "Another World" code and instead of going to the puzzle mode, go to Player Vs. Player. Once you get there you can choose your character. Depending on how far you have gotten in player vs. computer, more characters will be available. If you beat the whole game then you can choose everyone.