Activate the following cheats by entering the corresponding codes at "Unlock Menu" > "Options":
CHEAT FUNCTION - CHEAT CODE
Elite challenges - Y, UP, X, LT, RT, A.
Super strength potions - X, LEFT, RIGHT, A, RT, RB.
Stronger Protego Totalum charm - Y, B, UP, LEFT, RT, RIGHT (strengthens your Protego Totalum charm so that nothing can get through it).