Hello fellow summoners! Its been quite a while since I've been on MOBAfire, but during that time I've been playing League of Legends! If you have any suggestions for this guide, then feel free to comment. Also, please don't comment or vote before you have tried the build. Have fun!

Pros
Easy farming
Attacks slow target
Removes disables
Infinite distance ultimate
Great mobility
Good survivability

Cons
If kited then you become weak
If your W is on cd and you get disabled then you are screwed
Usually targeted first by most people

Gangplank is by far one of my favorite champs in LoL. He is all of my most favorite mechanics put into one character. Gangplank is not that hard to master. Once he has Ininity Edge he basically crits for half of his opponent's HP every time he attacks! Well, even though I have made it seem easy, he is not the easiest in the world of LoL. His ult requires some skill as to where to place it. (it can be the difference between life and death!) And without crit he doesn't deal a ton of damage. (he was built to destroy people) I hope you enjoy playing as GP as much as I have. Goodluck!

I believe that there are a variety of different masteries that can benefit GP. Low cd masteries make his ult be a lot more useful, but it lacks the damage output people want. All offense masteries gives summoners the ability to own, but only for a few seconds because they die instantly. There are many possibilities for GP! I've seen people tank with him! (they sucked at it but hey they gave it a shot! get it? pssh) GP is a powerhouse with his trusty cutlass, and his amazingly epicsauce gun. Yes, it is that awesome. Here's the shakedown:
I prefer using offense masteries because they increase crit chance and the amount of damage that your crits hit for (amazing if you ask me).
I like having increased crit damage because of the fact that only one item in game allows you to increase your crit damagge: Infinity Edge, and it is pointless to get two, or three....or six of them. You can increase your damage output by hundreds with these masteries! (This is not promising that your attacks will hit for 20 bazillion damage)

Runes:
I use basic attack runes for GP. I don't believe he is meant to do anything besides get crit and damage, so I use:
Armor Pen Marks(Very helpful in all situations)
AD Seals(They're ok, I honestly didn't think of anything else to put there. Extra crit damage seals are useful as well)
Extra crit damage glyphs (very useful considering without these and masteries your crit damage can only be 200% or 250%)
Armor Pen Quints(only so many items in game that provide armor pen, and none of those items are in this build, so I think that this is a must...in this build)

Gangplank is a pirate, you should have no trouble getting the gold for these items(at least I didn't)
For starters:
Boots of Speed-Ok
Brawler's Gloves-Great
Healing Potions-Must have these, no exceptions
Sapphire Crystal-Helpful

These are some of the best starter items for this GP build. All of these items are used to make better items in the build (exception for potions). There are other items that you could use, but I suggest these, mainly because of the fact that they will help you get that first blood, or help keep you from being the victim of first blood.

Core:

Trinity Force-This is something that I have found to be great on GP. I usually get this before Infinity edge because I believe that this is more of a priority than Infinity Edge. Reason: It provides:damage, survivability, mobility.
Infinity Edge-Pretty self-explanatory. If you do not use this then you better have something really good that you have replaced this with.
Boots of...-Choose your boots. Boots depend on different situations.
The Bloodthirster-Eh, this is kinda situational. If you are having long fights then this is great, but if its more of a run and gun type of deal then I would look for something such as a black cleaver or Last Whisper.
Situational:

Force of Nature-Great mobility and survivability. Good against heavy Magic Damage teams.
Warmog's Armor-Excellent survivability. Great for when you need a ton of health.
You should know the rest, if you don't well....

Gangplank is simple for this reason:
Parrrley is always and will always be the first spell that you should pick. Plain and simple.
I've tried leveling up my skills without putting many points into remove scurvy, but it provides you with a heal, and it disables disables, lol

Summoner spells are one the main things that makes LoL different from other games like it. They can be useful in so many situations, and different combos let you do more things!
Great choices for GP:
Flash
Ignite
Ghost
Exhaust
Good choices:
Smite
Teleport
Ok choices:
Clarity
Heal
Not good choices:
Clairvoyance
Fortify
Terribad choices:
Rally
Revive

I prefer flash and ignite for these reasons: Flash allows you to, well, flash over obstacles which would either grant you a kill or save you from mere death. And ignite, I love this and hate this at the same time. Ignite is great for when you are going against someone like warwick or xin zhao. Ignite reduces the targets healing by 50% for its duration. I can dominate Mundo, its sad at how much he nerfs him.

I hope this guide helps you in your LoL games. Goodluck to all of you and remember the summoner's code!