Mods? The console hasn't been hacked open yet, and besides, mods aren't legal in tournaments.
The console was hacked in a week, which is how we found out about the Yoshi game and the possible Metal Gear game.
Also, mods such as costume mods, stage texture mods, and music mods are legal in Brawl tournaments, as well as Brawl hacks (such as Project M, Balanced Brawl, Brawl Minus, and Brawl Plus) tournaments. Heck, technically those hacked games are hacks.
And yes, I do know about the Infinite Replay Hack for Brawl.
Those aren't hacks; I'm talking about real hacks; haven't you heard of the Brawl Vault=???
There's literally tens of thousands of hacks, from textures for stages and characters and the menus, to music hacks, to stage hacks (new stages, returning stages), to character hack PSA's (play as Mewtwo, for instance), to gameplay hacks (Project M, Brawl -, Brawl +, Balanced Brawl), etc. etc. etc. There's tons of hacks in Brawl, and there will be tons of hacks in Smash WiiU and 3Ds.
In that interview it sounds even more like my theory of said Yellow Devil being one of many character (Melee) Adventure Mode-esk bosses or mini-bosses is more likely than ever!
Also, good link find brah.
And that PlayStation All-Stars quote was golden, lol (but we'll still find a way to turn them off via hacks).