I know I'm a little late to the discussion, but I think I'll add my two cents in anyway.
Ever since I saw this little critter he's become my new favourite pokemon (move over aggron, new kid on the block), and while I agree he's a weak OU pokemon (or at least an extremely niche one), I do think he has a right to be there.
Hawlucha@Red card
Adamant
Unburden
Swords Dance
High Jump Kick
Acrobatics
Baton Pass
252hp, 252atk, 4speed
I've run a few sets on him, but perhaps the most effective one relies on no-one expecting him to be run like it. As we all know, hawluchas greatest assets are his +2 speed and attack, combined with a few really hard hitting moves. The red card means that he only needs to be hit once, from any move, and he's off. It catches the opponent completely off guard (if a bad poke gets thrown in, it even gives the opportunity to get another swords off, if you're feeling greedy). His speed is already more than respectable, so he has no use for extra EVs in speed (I put a few in there just to help him out, but they could happily go in either defence), meaning all that extra bulk results in him taking that hit far better than would be expected, often allowing a second hit from a non-super move.
The other trick in this set is Baton pass. If ever a poke this guy can't crack comes out, or would tear him apart even after boosts (in the OU game aegislash is the prime example) it allows a quick switch out to something that can kick it, all while maintaining the boost in attack.
The only thing I've found this thing can't take on is a talonflame (no duh), old swagger set Klefki (banned now anyway, so not an issue) or Sableye (and other similar pokes).
The biggest weakness is if it gets 1HKO (I run a screens setter to remove that issue), or the boost never happening from being burned/poisoned out. Because practically no-one expects a red card, I find it's rare that these happen, and the overall reward (he almost always takes out 2, often 3, occasional full team sweeps) means that it's worth the setup.
I've also tried one that runs stone edge instead of baton pass. Don't like it anywhere near as much, but is great for catching a few pokes off kilter, and have even beaten a talonflame with it. Not as recommended though.