Pretty awesome to have an archeopteryx Pokemon, and I dig the design. When I saw its base stats and movepool it seemed like it could have some merit, but once I discovered what that God-forsaken ability did it was difficult to really merit using it.
Even if its ability only halves Atk (though I am seeing some people saying it halves all stats save HP, which makes an already terribad ability even worse) its special movepool can't compensate. Its strongest special STAB is AncientPower, with no access to Air Slash or Gale is sight.
I can honestly see this thing nose-diving right into NU.
I'm gonna have to disagree with this post and the other naysayers. And that's not just bias, it's looking at what we know.
His ability is awful. No doubt. And he's not gonna get a new one, especially since he and the other 'handicapped' pokes have no Dream World alternative. Still, he is the best off of all Pokemon with a 'handicap' ability. Instead of being flat-out rendered useless NU-fodder like Slaking and Regigigas, he just has to adjust his strategy to a specific role.
OF COURSE, he's gonna die a lot! He's a frail sweeper to begin with! You can't keep him in against priority users, or Swift Swimmers, or blindly switch in and out with Stealth Rocks in play and then say "lawl he sux". He is built for a very specific role. Trying to shoehorn him into an Overpowered Superstar role is gonna leave you really disappointed.
Archaeos has a very specific set of tools that provide him with a very clear job which he can do very well. If you use his main advantages like Jewel/Acrobat and Claw Sharpen/Stone Edge/Focus Blast, in addition to playing smart and not just throwing him out there, he is a very potent player.
Late game sweeper/clean-up is the way to go. Just as with any poke, you have to play him to his advantages and not throw him into impossible situations, otherwise he's obviously going to be a letdown. If you work with his strengths and unique tools, however, he will NOT disappoint.
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