I see useless runes

ty psiguard

Walls of text and **** items -1

You can learn how to use BBcode here.

I personally would not start brawlers gloves as you lack sustain, and I also question the marks of crit, but that is just personal preference, either way I would definitely put more content and perhaps a match up guide. Reserving my vote for now but please archive, fix, and then re post. GL!

First 4 points in the offensive tree should be spent on Sorcery so you get quicker CD on your Q for farming early game. GP doesn't benefit much from AS.

Written part of guide lacks content.

-1 overall.

Ty for your feedback, I'll try to work on this, becouse I've never done guides before, if someone could tell me how to make BB codes I'd be grateful

Wrong runes, skill order, complete lack of coding, and this.

Cheatsheet
Starting Brawlers gloves is a bad idea, although the crit chance is helpful in lane it isn't a reliable source of damage or tank, so it's not really a good option. Not taking remove scurvy until level 13 is substantially worse, as it makes you super easily ganked and killed, as well as removing your ability to sustain. You put 9 in defensive, but don't get Veteran's Scars. Your runes are also questionable, but I've yet to try those so I don't know for sure. I'd at least suggest running Crit Chance instead of Crit Damage (if not going AD).

Main Guide
No coding, just colors that make it hard to read. Longer paragraphs that don't feel substantial (due to lack of coding and breaks, probably). I disagree with your last con, and kinda your first as well. Gangplank scales remarkably well, better than most bruisers, into the late game due to his ult, W, and E all allowing him to impact fights heavily even if CC'ed. GP has the highest HP at level 1 in the entire game, and that tankiness continues, unless you avoid taking W and avoid getting any tank until the end (which you shouldn't be doing)

Conclusion
This guide needs work, and BB Coding. Until either of those happens, -1