I'll agree that removing a character or two can improve things, but I disagree with the ones you listed greatly. Jigglypuff has been in since the beginning, so I think she's earned her right to stay. ROB actually plays pretty interestingly, plus he's a great callback to Nintendo's early history in games similar to Mr. Game and Watch. Lucario was much more fun to play as than Mewtwo(who is easily the most overrated Pokemon in existance), plus his mechanic of getting more powerful as he takes damage makes for interesting risk-vs-reward playstyles. Finally the secondary Link, while is somewhat clone-like, is different enough to warrant them staying. It isn't as pronounced in Brawl, at least not that I noticed, but in Melee there was enough difference between Young Link and regular Link to have both.
If I were to get rid of anyone, it'd be Falco and Wolf in their current states. Sure, there is some difference between them and Fox, but not quite enough to justify having all three. Especially when all three have their own physics which somehow makes them fall twice as fast when they jump compared to the rest of the roster. Barring them, maybe Lucas simply because only people in Japan are ever going to play Mother 3 at this rate.
