Judging by what you're saying, I'm assuming this is about lane-theon?
He is designed to be an early game bully, who is almost un-duel-able in early game, unless you have another lane bully. Otherwise if not, your own chance against his guy is either farming at the tower and roam, cheese 2v1 gank or you would have to squeeze your butt and hold on til much later.
Generally, he has an early game power spike, and it will spike again at 6 when he will start fly-ganking.
But all good things come to an end at some point, his power will decline over the game naturally. Assuming no significant feed, by the mid game he should really only be good at being a flying stun bot and a hunting dog who chases down lowered HP runaways, and he may also be seldom used as a backdoor'er but that's not too effective in general.
That said, it's for if you have to play around him. As mentioned, you can play with him by picking a duelist up against him in lane, assuming there's the drafting, and it makes handling him much easier.
If about jungle Pantheon tho, ward your lane openings, and keeps tab on his location after 6 and never over-commit because he will come down for your ass. That's really it.
He could be considered "broken" in a sense that games don't last long these days, which is good for him, but not that really because he is really broken innately.
/2cents