All Working Super Monkey Ball Cheats - GBA

Master code
Press [Down]x2, [Up]x2, [Left], [Right], [Left], [Right], [B], [A] when "Press Start" appears at the title screen. All bonuses and practice levels will be unlocked.

Blocky graphics
Press [Left]x2, [Right]x2, [Down]x2, [A] when "Press Start" appears at the title screen. The game title will change to confirm correct code entry. The game's frame rate will improve, at the expense of graphics quality.

Super speed
Hold [Up] + [A] during game play in any level and you will go much faster.

Slower speed
Hold [B] to go slower in the main game.

Beginner level 2: Warp To level 5
Instead of going forwards towards the goal, turn around and go up the little point. Fall off and land on a platform beneath. There should be another goal there that warps you to level 5.

Monkey Fight: Super power-ups
You can combine the power ups to create combos:

Big Glove + Big Glove = Double Glove
Big Glove + Long = Big, Long Glove
Big Glove + Vortex = Big, Vortex Glove
Big Glove + Big Glove + Long = Super Big, Long Glove
Big Glove + Big Glove + Vortex = Super Big, Vortex Glove