The reason it worked for those two in the show is because they were both much better singles players than their opponents.
Singles power can definitely carry you over teamwork if your opponents can't overcome your skill in splitting them up. If they are competent or nearly as competent in the 1v1 arena, then their teamwork will be the deciding factor.
Edit: To respond to Drift, the tier list is based pretty much entirely in 1v1. Some characters become much more viable in teams. Ganon is a lot more potent, Peach is an undisputed top tier teammate, Jiggs gains a couple of spots. One character who is much better in teams, although not to a very useful extent, is Kirby. Any character with good defensive strategies and survivability makes a great teammate; this is why you see Falco performing much less effectively in teams than in singles. His aggressive, high risk high reward style does not shine in the 2v2 arena nearly as much in 1v1s. He's still pretty effective because he's such a good character, but I'd argue that he drops a few places on the list--if only because quick KOs can drastically change the flow of a 2v2 and he's extra susceptible with two opponents on the field.
