Dark Summit Cheats (GameCube)

Jump and press z and you can jump backwards

  

In the level Summit and the objective feed the bear, you have one
  minute to find the bear cave.  Just stick to the right and follow
  the signs.  When you get there you'll see ranger dick.  You
  have to escape from him.  He follows your every move so be
  careful.  You can hold R for more speed.  Go to the forest
  and Weave through the trees.  He will follow your moves so make
  him hit the trees and he will fall down.  Keep doing this and you
  will be way ahead and then you can finish.
  

  

  

Beat the game with Naya and you'll have all secret characters to play
  as in 1-player.