Sorry then, came off as too aggresive. I've been pretty stressed recently
I still have to disagree however.
Triple barrel (I assume that's what you refer to when you refer to his E cheese) was a part of Gankplank's kit since conception, infact in the Champion spotlight Phreak points it out. Using it sounds like a way to negate counterplay, but it costs Gangplank a lot.
People say that his barrels are op because they are resourceful, but because of how powerful they are, they are a resource in themselves. When you do a triple barrel, you waste all of your barrels, which means that you are going to be out of a reliable escape soon because barrels are the main way that you disengage fights. In teamfights, you lose the ability to drop a barrel and pop it quickly because of it's low health fall rate. When you triple barrel, it better hit the backline or else you will be losing a lot of damage for not a lot of payoff.
In the lane phase, the damage is weak and GP has to use all of his barrels to do it. If he uses it on you, try to engage on him after since he'll likely be lacking barrels. You can dodge it with any sort of mobility or shielding, it's fairly predictable. In fact I rarely use this combo in the lane phase, at least vs melee toplaners, since I'd rather just keep myself safe with barrels, freeze the wave, and poke out the enemy with Q. I'd be more worried about his Q poke than his barrel combos if I were melee.
I don't think he needs nerfs or changes. But if he had to have them, I'd nerf his slow/ms from procing barrels or passive, instead of removing the triple barrel. He gets so much safety from this that he gets to control the lane phase despite being a late game monster. If you get the jungler to come up there, however, he's pretty boned.