Bully Cho'gath early game to take advantage of his beginning low damage, low CC durations, contextual healing, and easily avoided damage. Seriously. Just harass him EVERY time he tries to CC, if you do that and just watch for when he Q's and then all in him pre six it's pretty easy to kill him / zone him EXTREMELY hard at most stages of the game.
Even if he gets to late game and is super big you just need to bait out his skills. They have large cooldowns and Q is very avoidable. He's also durable due to ROA + ulti stacks but, if building mage (which is the only time he's extremely dangerous), a massive immobile target which will die in about 4 seconds if he misses his Q.
In fact, the only part of cho which may need to be toned down is his early game auto attack damage with E. Yet even that is pretty important, given how large his cooldowns are and how each of his other abilities costs nearly 100 mana at all levels.