He can still find a niche in OU I imagine. You just need to make use of his toys that separate him from Machamp/Roobushin.
Hariyama @Leftovers
EVs: 252 HP / 252 Def / 4 Atk
Nature: Bold
Ability: Thick Fat
~ Close Combat / Force Palm
~ Ice Punch
~ Stone Edge
~ Knock Off
If you use him in OU, you need to use his toys like Knock Off and Force Palm. Ice Punch and Stone Edge prevent him from getting walled to death by Gliscor and other fliers.
As this set mainly answers Doryuuzu, I put some calcs up:
369 Atk vs 240 Def & 492 HP (100 Base Power): 216 - 255 (43.90% - 51.83%)
That's an unboosted Earthquake on Jolly 252/252 Doryuuzu vs the spread I posted. Abysmal chance of a 2HKO. SD sets once again have an abysmal chance of a OHKO with a boosted EQ, and a Life Orb. Balloon sets die to this thing and can only manage a 3HKO, as it's mainly balloon variants that threaten my team. Now, as for Close Combat...
276 Atk vs 168 Def & 361 HP (120 Base Power): 422 - 500 (116.90% - 138.50%)
Not the most elegant solution, but it works. You might consider Encourage to boost the strength of Stone Edge and Ice Punch, and you definitely need it if you're running Force Palm to give him a much-needed boost, although sacrificing the paralysis chance isn't the best idea...