Originally Posted by Sorgklaan
But that's the whole point, I want to play critplank in ranked. :|
It is possible to play Critplank in ranked, if you are good enough, just as it is in normals. HOWEVER, since GP is currently a second tier top lane, he is best considered as an "invitation only" champion. What I mean is that he should never, ever be a first pick. There simply too many counters and strong options to shut him down.
If I am team captain and I pick GP right away, the enemy knows that it is practically a guarantee that I am going top with him. They have a choice of counter picking Fiora, Jax, or Pantheon to make my parley completely ineffective, rendering my options for dealing damage practically zero. If they do not want to play any of those champs, they also have the option of going with Jayce, Yorick, Kha'Zix, Olaf, Nidalee, or other champions with better burst, range and sustain. First-picking GP is basically surrendering top lane right from the champ select screen.
HOWEVER, if you are one of the last people to pick, and you are fairly sure that their Shen, Nasus, Cho'Gath, Garen, or another fairly passive, farming champ with low burst potential is going top, then consider it an invitation to play GP. Rather than playing aggressively out the gate, just out-farm them until you can get your crit chance up so that you become a major threat mid-late game.
My Critplank build is Infinity Edge, Phantom Dancer, Youmuu's Ghostblade, Warmog's, Iceborn Gauntlet, and Merc's Treads. With my 20% crit-chance rune page, this finished build gives me a 9/10 chance to crit, along with enough survivability to not die instantly, a spellblade that procs and slows every parley, some armor pen and an extra speed-boost for chases and escapes, everything a critplank needs and more. For masteries i go 4/22/4. The defense is to help compensate for lack of armor in early levels before I finish Iceborn, and gives me safety as I concentrate on building crit-chance and offense items.
Hope this helps and remember to always pick GP responsibly, good luck in solo-queue.