Mienshao@Life Orb
Regenerator
Jolly/Naive
252 Attack/252 Speed/4 HP/Sp.Atk
~Fake Out
~U-Turn
~Hi Jump Kick/Drain Punch
~Stone Edge/Hidden Power (Ice)
Mienshao is an extremely unique individual. For one thing, it gets Regenerator without the need for the Dream World. It also gets U-Turn, which makes for an excellent strategy. What you do is, use Fake Out for some free damage, maybe use the bottom two moves to inflict more damage or stuff, then switch out with U-Turn. Thanks to Regenerator, this means that 1/3 of Mienshao's total HP will be restored. This will fully heal Mienshao if it's taken three turns' worth of Life Orb recoil. Hi Jump Kick and Drain Punch are your STAB options. Hi Jump Kick's inclusion is obvious- upped to 130 base power. That said, it still only has 90% accuracy, and all it takes is for that move to miss ONCE and Mienshao is toast. In addition to losing half its max. HP, Mienshao is now at the mercy of the undamaged opponent. And with defenses like that, it can't really afford to be at the mercy of any opponent. Drain Punch is a weaker, but more reliable option. Plus, it can assist Regenerator by healing Mienshao as well. The last slot is up to you and will basically also decide on the nature and those last four EVs. Stone Edge and HP Ice are both good for extra coverage. Stone Edge means you should run a Jolly nature and put those extra EVs in HP. HP Ice, Naive, Special Attack.
Regenerator is the only ability any sane person runs on their Mienshao. Inner Focus is moot, as Mienshao's not gonna be surviving any attack long enough to flinch anyway, and as for Reckless, not even considering the fact that Mienshao can't even legally get it yet, it can only abuse it with Jump Kick and Hi Jump Kick. Not exactly the best trade-off for the opportunity to heal off that Life Orb damage.
Mienshao@Flying Gem
Regenerator
Jolly nature
252 Attack/252 Speed/4 HP
~Fake Out
~U-Turn
~Acrobatics
~Hi Jump Kick/Drain Punch
I used this strategy myself to good effect, before I got access to a Life Orb in my Black version. It's simple, really. The usual Fake Out, and then use Acrobatics. With help from the Flying Gem, Acrobatics reaches insane power levels. Even after that initial usage, it remains at an amazing 110 base power. Hi Jump Kick and Drain Punch are, once more, your STAB move choices. U-Turn won't be seeing as much use, because there's no Life Orb recoil, but Mienshao still won't exactly hate the opportunity to heal off entry hazard, sandstorm, hail, etc. damage. Won't be able to heal off attack damage, though, because that generally requires the Pokemon to be able to survive attacks.
Mienshao@Life Orb
Regenerator
Timid nature
252 Special Attack/252 Speed/4 HP
~Aura Sphere
~Hidden Power (Ghost)
~Grass Knot
~Swift/U-Turn
What a shame. Mienshao has such nice Special Attack, and it squanders it on a movepool like this. What you see here is literally its entire usable Special movepool. And even then, note the presence of Swift, of all things. Yeah. But anyway, Mienshao does have the moves, and therefore does have the capability to throw together a decent special set. Aura Sphere is probably the one redeeming quality of this set. Precious few Pokemon have access to this attack. Most other Pokemon looking for a special Fighting move have to go with either the scarily inaccurate Focus Blast or the woefully weak HP Fighting. Aura Sphere, however, has 90 base power and never misses. Those Sand Veil Garchomp, they're not laughing now, are they? HP Ghost provides absolutely perfect coverage alongside Aura Sphere. Despite my earlier slight on Hidden Power, it is a necessary evil. Mienshao doesn't even learn Shadow Ball! Anyway, Grass Knot is good for particularly heavy opponents (Swampert comes readily to mind). Hell, if you're feeling especially daring, you can even use Mienshao in Ubers, try to OHKO yourself a Groudon with Grass Knot. The last slot is up to you. U-Turn is really the move you should go with. Despite the fact that this Mienshao is not geared to use physical attacks, the real appeal in U-Turn is the whole switching thing, and activating Regenerator. I only threw Swift in there for those of you out there that don't feel that a special attacker should be using Physical moves.
Mienshao@Leftovers
Inner Focus
Jolly nature
252 HP/128 Defense/128 Special Defense
~Calm Mind
~Bulk Up
~Drain Punch
~Stone Edge/Hidden Power (Ghost)/Baton Pass
Yes, I know perfectly well how absolutely insane I am to even suggest a set like this. Yes, I am perfectly aware that I used a lot of this post to rip on Mienshao's pathetic defenses. And yes, I am perfectly aware that right now, I am suggesting a defensive set for Mienshao.
Here's the thing. Mienshao gets Calm Mind and Bulk Up. Chances to boost not one, but both of its defenses. Granted, it can't boost both simultaneously, but with prediction (and a heaping helping of luck), it can get both defenses up to manageable levels. Drain Punch runs off of the Bulk Up boosts to Attack, and is a means of healing Mienshao. As for the last move, there's several options. You got Stone Edge, another move that's good for coverage. You got HP Ghost, not a bad idea. Perfect coverage, and the Jolly nature won't matter much if you get enough Calm Minds going. And you got Baton Pass to give them boosts to something else.