Originally Posted by Fat Acritter
Archeops, easily. It is capable of some VERY powerful blows on the physical spectrum (with some special backup), is viciously fast, and has great coverage. It can be used to knock holes in teams or clean them up, and although you can't switch it in on much it's a great recipient of slow switch moves and great for bringing in after deaths. Its primary weakness is, of course, SR, but it's still a fantastic Pokemon provided you have a team that needs what it can offer.
Archeops has 2 main reasons why it isn't OU worthy.
1) The biggest most obvious one is it's ability defeatist. When it gets below half-health, Both of his attack stats falter by 1/2. As a result he can't run hints like focus sash sets or even switch out with U-Turn because if rocks hits twice Defeatist auto activates.
2) Thus reason is much smaller and can almost be overlooked, However if he had a goodFlying type STAB technique, like say BraveBird. He'd be alot better, because all he really has is acrobatics and in order to use acro, you need a flying gem.