I know maybe all possible tricks in the Brawl. I can write some here. I mostly use the Gamecubecontroller, so I'll explain buttons here with gcn-style.
-When playing as Samus, if you press the up and down taunt buttons repeatedly really fast (like up, down, up, down, up, doen, up, down in like less than 2 seconds), you will transform yourself to Zero Suit Samus without having a Smashball. This is good in two ways: 1. If you like to play with Samus and you suck with ZSS, and you have a Smashball, then you can transform yourself to ZSS and then use the Smashball to become Samus again. 2. You like to play with Zero Suit Samus and you suck with Samus, then this is perfect for you! ... Or you can be ZSS from the start of a match and never transform yourself... But this way is much cooler. If you want to learn this, you should first try it in training mode at a slow speed, and then do it in less slower speeds untill you learn this in normal speed.
I know a good trick with ZSS, but it maybe don't fit everyones fighting style, but I like to meteor smash/spike my enemies, and ZSS can do that not only with her up+B and her down+A in air, but also with her down+B,B attack if she manage to kick someone from above and the enemy is in air. But this can get you killed because it takes a while untill you can move again after the attack, and you can't do your up+B after the attack, but you can jump if you haven't allready jumped twice.
-When playing as Pit, try to not get hit while you're flying with your up+B, because most of the times you can't use it again. If you're battling Pit, then you should try to hit him while he's flying.
If someone shoots a thing on your shield, it will be reflected and do more damage than before. If two Pits stand in front of eachothers and a projectile is reflected by one of them, and the other reflect it to, and they do it again and again, after a while one fo them will get hurt, and he will get much more damage than the projectile usually does, and the Pit will probably be knocked of the stage.
-If someone have made you slow-mation, and you are playing with Ness/Lucas, then use your PK Thunder, it's still fast!
-If you're playing as Pokémon Trainer, and someone used the Thunder item that makes you small, press down+B and change Pokémon and you will be normal sized again.
-If youre playing as Zelda/Shiek, adn someone used the Thunder item that makes you big (a corrupted one), press down+B and change character and you will be gigantic the whole match, or untill you die. Don't do this if you are small
-If you are playing with Jigglypuff, and a bomb box (don't remember what it's is called) is nearby, press down+B on it to detonate it, and you won't get hurt!
And if you are Shiek, use your up+B to blow up the box and you won't get hurt
-Don't play as Sonic, because he's cheap.
-Donkey Kong can walk really fast and jump even when he is holding a heavy item.
-If you're playing as Bowser in a stock match, and you and your enemy have one stock left, use side+B on the enemy and take a "suicide" with him, you will win the match, because he is under you and will get outside the stage first.
-Link's and Toon Link's shield can protect them from projectiles.
-If Jigglypuff gets shieldbreaked, he will fly of the stage.
All of theese did I discover myself. I might add some more some other time, I'm too tired right now...
-When playing as Samus, if you press the up and down taunt buttons repeatedly really fast (like up, down, up, down, up, doen, up, down in like less than 2 seconds), you will transform yourself to Zero Suit Samus without having a Smashball. This is good in two ways: 1. If you like to play with Samus and you suck with ZSS, and you have a Smashball, then you can transform yourself to ZSS and then use the Smashball to become Samus again. 2. You like to play with Zero Suit Samus and you suck with Samus, then this is perfect for you! ... Or you can be ZSS from the start of a match and never transform yourself... But this way is much cooler. If you want to learn this, you should first try it in training mode at a slow speed, and then do it in less slower speeds untill you learn this in normal speed.
I know a good trick with ZSS, but it maybe don't fit everyones fighting style, but I like to meteor smash/spike my enemies, and ZSS can do that not only with her up+B and her down+A in air, but also with her down+B,B attack if she manage to kick someone from above and the enemy is in air. But this can get you killed because it takes a while untill you can move again after the attack, and you can't do your up+B after the attack, but you can jump if you haven't allready jumped twice.
-When playing as Pit, try to not get hit while you're flying with your up+B, because most of the times you can't use it again. If you're battling Pit, then you should try to hit him while he's flying.
If someone shoots a thing on your shield, it will be reflected and do more damage than before. If two Pits stand in front of eachothers and a projectile is reflected by one of them, and the other reflect it to, and they do it again and again, after a while one fo them will get hurt, and he will get much more damage than the projectile usually does, and the Pit will probably be knocked of the stage.
-If someone have made you slow-mation, and you are playing with Ness/Lucas, then use your PK Thunder, it's still fast!
-If you're playing as Pokémon Trainer, and someone used the Thunder item that makes you small, press down+B and change Pokémon and you will be normal sized again.
-If youre playing as Zelda/Shiek, adn someone used the Thunder item that makes you big (a corrupted one), press down+B and change character and you will be gigantic the whole match, or untill you die. Don't do this if you are small
-If you are playing with Jigglypuff, and a bomb box (don't remember what it's is called) is nearby, press down+B on it to detonate it, and you won't get hurt!
And if you are Shiek, use your up+B to blow up the box and you won't get hurt
-Don't play as Sonic, because he's cheap.
-Donkey Kong can walk really fast and jump even when he is holding a heavy item.
-If you're playing as Bowser in a stock match, and you and your enemy have one stock left, use side+B on the enemy and take a "suicide" with him, you will win the match, because he is under you and will get outside the stage first.
-Link's and Toon Link's shield can protect them from projectiles.
-If Jigglypuff gets shieldbreaked, he will fly of the stage.
All of theese did I discover myself. I might add some more some other time, I'm too tired right now...