...Super Smash Brothers is a very sophisticated form of "king of the hill" where whoever stays on the stage/hill the longest wins. It sounds like your brother doesn't know the point of playing this game, eh? The point is to keep your opponent off the stage or to knock your opponent off the stage. You may use anything in your character's arsenal to do so. The point is to be the last man standing.
If you weren't supposed to be able to edgehog/edgeguard, THERE WOULD BE NO EDGE TO GRAB. Or, your character would -instantly- climb up onto the stage with invincibility frames to protect you. The point is, the game is designed so you can hang on the ledge for an indefinite period of time. It was made that way.
Now, your brother is just reinventing a new game. A "lets not use this, this and this" kind of game. That's perfectly fine, but you should have the heart to tell your brother he isn't playing Smash Brothers. He's being a scrub. He's using his own set of fake, nonexistant "fair" rules. If he wishes to play that way, all the power to him. You can't really force him to play differently. My suggestion: Get new opponents. Or better yet, make friends and play with them. Your brother is just upset that you utilized an element of the game that he never thought of, and beat him with it.