I just went to the RMT forum and looked at the first 15 OU teams posted there. I counted the number of pokemon on each team that carried a Ground, Fighting, Water, Grass or Steel attack. Here's the results:
6, 6, 4, 5, 5, 5, 5, 5, 6, 5, 5, 6, 6, 5, 6
I realize this is a laughably small sample, but still. Basically every team has 5 or more pokemon that can threaten our rockmon with a super-effective move.
Let's face it, there is a reason that Rock pokemon are rarely used in the metagame -- Rock is a shitty type! Rock pokemon have huge problems coming in, because every team is stacked with pokemon that can kill them. Heck, one of those teams above was MONO-FIRE and they have 5 pokes that can knock the hell out of CAP5! Think about that for a second. Our pokemon resists Fire and hits it SE -- and against a mono-fire team, our rockmon will have trouble switching into 5 of them. That's scary.
In my little RMT run, the pokemon that DIDN'T have an attack for CAP5 was stuff like:
Blissey - I didn't count Seismic Toss as a Fighting move. But, it doesn't matter. Blissey giggles at our special attacking pile o' pebbles.
Cresselia - Even she can carry Calm Mind and give problems to our guy.
Jolteon - Yay! We finally found a pokemon that CAP5 can safely switch in on without getting smacked for SE damage! Oh wait... it'll probably just Twave us and completely ruin our day... damn.
I'll stop there. My point is that even the pokemon that couldn't threaten CAP5 with direct attacks, were not exactly safe to switch in on. Oh, and for those that point to this pokemon's majestic 120 special attack -- remember that our pokemon has the misfortune of being weak to some of the most defensive types in the game -- Steel, Water, and Grass. That means pokemon like Gyarados, Metagross, Heatran, Celebi, Bronzong, Suicune, Swampert, and Vaporeon are licking their chops.
Without a movepool and ability, it's hard to say what this pokemon can threaten and what pokemon will threaten it in return. But, based on typing and stats, we have some HUGE problems to overcome in the current OU metagame. I know people don't want to go overboard with this pokemon -- and I don't either. But, our Rock pokemon has its work cut out for it. Right now, I'm less concerned about all the things that will make this pokemon broken. I'm more concerned about figuring out how to make this pokemon viable at all.