Frostwraith
The Demon King
Wolf as a DLC could be a good way to advertise the next Star Fox game, for example.Well, the other alternative is outright stopping players from playing with those who bought the DLC (be it characters or races). It would end up in a huge split between the two communities, and it's a pretty awful outcome, all considering. Same for Smash in a way : could you imagine people with DLC characters unable to play with people who didn't buy them? The online would be a complete mess.
As for DLC characters, I just hope Nintendo has plans with the Mother series to justify Lucas being DLC, I'd love the little guy to be back, since most of the others cuts (barring Ice Climbers) would be shoo-in.
I think a veterans pack with at least Lucas, Wolf and Mewtwo would be pretty great.