Support Gangplank -- a gift from the sea
Hey there, Onwodori here.
Just gonna drop it on you this time.
Support GP was strong but it was on the DL. After his rework, it is still strong but more difficult. How it works:
Your summoners. You're going to go 0/12/18 focusing on taking Bandit, the summoner spell CDR and Grasp of the Undying.
Your selected first items. Start with Q. Poke constantly with it, and smile in surprise as you do notable damage and receive 15 gold per Q-ing someone -- that's more than some small jungle creeps.
Get this ASAP. If you need to get 500 gold, back and teleport to lane, do so. GP support is all about keeping up the never ending poke in lane and bullying them to death. You now get 25 gold per Qing someone and do more damage.
You are going to put a point in Q first and leave it there. Take E or W second depending on whether you need sustain and the cleanse to shut down certain lanes (Thresh, Leona, Bard) anything that wants to CC you for a kill. E is for warding the river and bushes. Take a point in all 3 by level 3. Max W first for sustain. This isn't a kill lane UNTIL you get them very low from constant, abusive Q's.
When you hit 6, start watching your map even more. You have a global AOE slow that does notable damage if they stick around too long. Use it well.
When poking, wait for your Grasp of the Undying to be ready to deal even more damage and recover HP.
Rush this after your Frost Fang. This will give you the mana you need to poke so frequently. You don't need a Sightstone first item due to your E being used for vision. Poke *constantly for 25 gold per shot and to push them under tower.
Your core is as such:
with either
All having their uses.
You have now become a brutal poke, perma slow bruiser with a respectable gold income from getting a melee minion worth of gold ever 5 - 3 seconds.
Build tanky, focusing on armor, HP and utility. Ironically,
is perfect (Lore mates.)
I'd imagine a full build would like something like:

Have fun being a rich pirate support, friends.
-Onwodori
tl;dr 15 to 25 gold per using Q. Perma slows. Free vision. Fantastic lane bully. Shuts down kill lanes. Worth considering due to GP's nerfs.
For early damage and ganks
and probably a
but then it's getting expensive. Max Barrels for clear. Take
over