So SSB is really an advanced AI that can evolve beyond its original code?
If you can do it in the game, then it's in the coding. Period. Whether this was an unintended loophole the designers overlooked is irrelevant. It's still allowed by the game, or it would not be possible to do.
Also, tournament play is the highest level of play, thus those rules are the law of the game.
So, if it's possible to do in the game, and is allowable in tournament play, then it is in no way shape or form cheating!
This is of course excluding the previously mentioned casual play rules you and your friends set up.