/rant I haven't downvoted yet... but I damn well may. Same goes for your Poppy guide.

Clarity is a crutch. GP has limited escape options. You already have a heal/cleanse that heals for MORE THAN HEAL. This guide is bad because he absolutely doesn't need a frozen mallet, that is expensive as hell and provides barely any AD. Youmuu's ghostblade is tremendously better for the price... It was practically MADE for GP.

Take Flash/Exhaust or Flash/Ignite. Really dude. Your masteries are odd... This is tankplank without all the health or durability. You're so lacking in damage that I can guarantee this is gonna be reeeeeeeeaally hard to carry with..... Frozen Mallet is just unacceptable! All that money, for almost no damage? Seriously, Doran's blade at the start??? Unnecessary! He doesn't need the AD, and rather than just getting brawler's gloves, which actually builds to things he needs, you pretty much throw the money away... it's health he doesn't need, it's not enough lifesteal to really matter, as you don't have the range to farm on auto attacks. You talk about reaching your full potential with this build, when you get so little crit chance, waste money on a Doran's Blade, a Frozen Mallet, and absolutely GIMP your damage with your masteries, runes, items, summoner spell choices.... -1. Please understand. I'm an *** when it comes to Gangplank guides, because I've played like 300+ games with him before I switched mains. If I saw a Gangplank take him from me, and abuse him like THIS, I would be seriously pissed. Change some things.