Combo king: before you enter the mojo room there is a cage hanging on your right side with a Shellephant in it. If you have an ee-lectric continuasly use it's regular attack on the shellephant. After some time you will complete the combo king "challenge"
Minion Master: You just have to defeat every minion you see and, while you are defeating Uka-Uka, you will complete this "challenge"
Spybots: The spybots are the easiest part. You don't even have to look for them. As you progress through this level you will easily find all of them.
To modify the character 'Crash' pause gameplay and enter either of these two codes for the version of Crash you want. To disable the effect and return the game to normal just pause the game and enter the code again.
Unlock Big Head Crash: Hold R1 and press Square, Square, Triangle, and X.
Unlock Invisible Crash (Shadow): Hold R1 and press Triangle, Square, Triangle, Square, X.