The competitive SSBM discussion thread

Huh, are you kidding me? Just beat any 1 player mode game. (Classic/Adventure)

Do you mean Brawl, where you need to play hundreds of matches to unlock her? xD If that's the case, the fastest way is to do Special Matches. Activate Stamina and Flower, and set the computer's HP to 1. Just keep "playing" matches till you unlock Jigglypuff.

? One play through of SSE unlocked every single player in the game except toon link for me. Including jiggly.

Fair/Bair is usually the way to go. Dair is meaningless. Nair has no knockback. Uair sends them up so they can recover with DI more easily. Forward B will knock them towards the stage if you use to away from the stage; i.e. Forward B pushes people behind you. Last I recall anyways.
Sing is pretty useless in both versions, I would say. I've seen maybe two Sings in competitive play in person (that wasn't stalling death from falling). They were both just completely random things that caught someone off of a tech.
Edgehogging in Brawl is more difficult but it depends on the character you're defending. Brawl+ doesn't have auto-sweetspot from what I know, so edge-guarding with a Forward Smash would probably be the easiest choice against most people.

In brawl i'm pretty sure pound pushes the character upwards, instead of behind you like in melee. Doesn't really change much, though, since what you said is still kinda true.

Jiggly is super fun once you get to picking up aerial attack speed with her. ^-^