And that's the thing. It's, for all intents and purposes, a popularity contest.
Personally, I think that, when it comes to fully evolved Pokemon at least (although I've seen someone use an Eevee competitively, usually to good results) all Pokemon have can be useful. In my modest opinion, there should only be two tiers: Uber and "other." Anything that doesn't qualify for the former, falls into the latter. Plain and simple.
I personally play the standard tier on Shoddy with a combination of OU and UU Pokemon and I win my fair share of battles. I defeat entire OU teams all the time with Pokemon like Houndoom, Venusaur, Feraligatr and Meganium. I also get defeated all the time and not always by OU teams.
This leads me to rely on tiers very little. I think it all depends on the player, his/her strategy and how well they can pull it off. Different strategies will require different Pokemon, and some pretty successful ones work better with Pokemon that aren't OU.
That's just my opinion though. If tiers are necessary, at least don't make them about popularity (yes, I know that popularity tends to stem from usefulness in battle, but I just think that, if they must give us a tier list, they should completely skip the "usage" part and concentrate on their statistics, strategy and general usefulness alone.)
Smogon's been frustrating me lately for this particular usage reason. One moment Umbreon's OU, the next he's not. But Roserade has become OU now, and Alakazam got demoted. Charizard's suddenly an NU and Rhyperior's a UU. But next week, it all might change again and Alakazam might get promoted again but Roserade might get demoted. With all this up and down travelling for the Pokemon, who's to say which one is really useful in the standard tier anymore. Then there's Pokemon like Shedinja, Ninetales and Primape, who don't make it to the current standard tier because they can't "handle themselves in it," but are actually pretty solid in the Uber tier, where all the legends roam...it's confusing, frustrating and annoying in my opinion.
Yes, I know I'm probably going to get bashed for saying all of this, but it's my honest opinion and I'm just throwing it out there, so I have no problems with whatever backlash may come from this post.
