Unless it is someone actually cool and deserving of it, like Mario or G&W. =P
Eh, Tiers should not be the main focus right now, it is way too early for this stuff... At least give yourself some time to enjoy the game before it grows horribly stale from everyone using the SAME character because of the high chances of winning...
I was never a fan of tiers at all, and in Melee, Ness was considered low tier after being in the top in the 64 version but that never stopped me from playing as him competitively, in fact the struggle against harder opponents kept the game alive for me and I got to learn all of the strategies competitive Fox, Sheik and Marth players they possessed in tournaments, and thought up of some strategies of my own to beat them (Oh yes, it is very possible)...
Sure many were skeptical of the thought of a great competitive Ness player, but in the end they are quite surprised to be beaten or even going through a neck and neck near-miss fighting a Ness player...
My point is, If Fox was lower tier, even on the off chance of him being in the lowest tier (which is unlikely, but hypothetically). Would you still try to use him competitively because you like him as a character? Or, would you just totally give up on him because of him getting nerfed a bit so he's not totally broken anymore?