@Cheza- I did that Stage Builder thing you suggested, and fought 3 CPU opponents at once in it. It was glorious.
That has got to be the longest Sudden Death match I've ever played in the history of me playing Brawl. I was stuck fighting Fox, Lucario and Wario. Fox lost the normal match (somehow), so I was in Sudden Death against Lucario. After about five minutes, Lucario got himself sent flying out of that tiny little opening by a Bob-omb, so me and Wario were at each other for like seven minutes. In the end, I somehow won, even though my damage was at 734% and Wario's was at 612% or something like that. I was using Meta Knight, of course, so maybe spamming his up attack helped. All of those Bob-ombs raining from the sky, though... I hate it when they do that in Sudden Death if you take too long. xD