Well, let's take a look at a few example sets...(assuming Growth, since that seems to be the main stat-up move that's being considered)
Growth/Fire Blast/Energy Ball/HP whatever loses solidly to Blissey (status isn't even necessary, Bliss can just wear this thing down with Ice Beam/Toss since it has no recovery and it's going to be doing lol% damage to Bliss), Cress (same reasons as Bliss), Snorlax, Togekiss, Tentacruel, and a whole bunch of other stuff depending on what Hidden Power type it's packing.
Growth/Fire Blast/Energy Ball/Rest wins against (non CM) Bliss and Cress, but still loses to Kiss, Lax, Tenta, and can't even begin to threaten Heatran. You've also got to deal with things coming in and phazing or just killing you while asleep.
Growth/Fire Blast or Energy Ball/Rest/Sleep Talk...err, ripped to shreds by Heatran and everything else the above set loses to.
I really don't see how just Growth will make this Pokemon overpowered. Physical is a bit more worrisome as far as counters go since most physical walls are weak to Fire or Grass, but Gliscor with AA (which is all the better of a choice to hit those Revenankhs and Syclants) or Stone Edge would work great, Gyara could probably do the trick, same for Salamence...it depends on exactly what we give it.