During the character select screen press and hold the following:Down+L+R and select your character. You now have access to all your hidden special attacks and desperation attack.
Constantly press B,A,X, and Y during the Jaleco logo until you reach the title screen. When successful you'll reach a black screen. It is actually the title screen. Press start once and then press up once to move to the options because you cannot see the screen properly. When you exit from the options the game will now change to "Brawl Brothers".
To play as the easier Japanese version, sequentially and repeatedly press B, A, X, Y at the white screen with the Jaleco logo until it disappears. If done right, you'll arrive at a glitched screen. Now, press Start, then Down three times and Start again. You'll be at the options screen and when you exit, you'll see the Japanese title screen. Now start your game and enjoy the original version of the game.