Another random thought: Scizor might not be a bad partner. Much like Tyranitar, it takes Psychic crap rather well and has Pursuit (pseudo-STAB if the opponent doesn't switch out) with Technician Bullet Punch to back it up. As far as priority goes, Mach Punch + Bullet Punch should hit the vast majority of the faster Pokemon at least for neutral damage. The only exception is something like Denchura.
Not to mention Scizor can U-turn, which leads to easing Roobushin coming onto the field and what not. Of course, Roobushin doesn't really absorb some of Scizor's problems, so it is a bit one-sided (for example: Scizor hates Heatran. Roobushin handles Heatran? Not so much...). Guess it doesn't really get much better than Tyranitar as a partner despite the loss of Leftovers recovery. Croc works too to an extent since at least it's quick enough.
Scarf Genosekuto can work in a very similar way like Scizor and can threaten Gliscor, Skarmory and Psychics, Dragons that love to come into Roop easily with his exceptional good coverage.
he isn't as bulky as TTar and Scizor are though, but works great on more offensivly minded teams.