There won't be any defined tier list until the game has worldwide tournament play.
Expect an early tier list maybe in a half a year after the game's release. Remember that tiers are a reflection of high level play. So unti the tournament scene has some significant time, don't expect one.
Also, understand that the tier list is not something that is set in stone. Melee's tier list fluctuated as people got better at the game. Falco for instance, changed a lot when people figured out first how to short-hop laser, then how to pillar.
Expect early tier predictions within the first month of tournament play. But I wouldn't count on an agreed tier list for a while.