I've played Gangplank a fair amount. I build as a crit heavy carry, using Parrrley to harass and last hit minions. His ulti seems to be a li'l lackluster to some but I mostly use it to defend or push towers when a champion isn't around. It destroys minion waves, providing only the tower to target for your minions. Or prevents the minions from destroying your tower. His CC break/Heal plus enhanced movement speed allows him to escape fairly well. AS/MS boost for his team during pushes means Gangplank provides some team utility if played right.

Looks like only Obsession really answered your question, everyone keeps their dream team secret:P You will be answered once replays come out, until then, testing is your best friend, and it all depends on the greatness of your friends with specific heroes.

I'd say most of your comments are right, few seems not. Pretty sure Singed is on the good side (tons of hp, poison to clear creeps/farm, nice slow and throw), and I'd give more credit to Morganna than you did, same with Karthus. Morganna's shield is just awesome.

Until this patch, a tank heavy team with support would give you a good chance to win, with the new heroes and tweaks, might be not as good (but still good).

Soon as i read this i disregarded the entire post. Singed=Great team player.

Anivia is probably the hero picked in every premade. Flash frost lvl 1, and max frostbite is pretty much instant kill on anyone who isn't a tank. The range on wall makes it impossible for enemies to run through the jungles, and her ultimate has amazing range and isn't even channeling, allowing her to cast wall to prevent enemies from exiting it. 95% of games have her as solo, and carry.

Add Amumu and Blitzcrank in there to support her ultimate, Tristana for physical dps, and either morganna or Fiddlesticks for disables, and you pretty much have team fights in the bag.

Did you say singed, probably the best initiator in the game, sucked?

If you see Sion going with a tank build they are probably going to feed or not contribute a thing to team fights. He's dps. If you ever see a Sion take sheild at any level before 14 just facepalm and prepare to watch fail.

Tristana can be very handy in team fights. I often find new uses for Buster Shot (like blasting Nunu away as he's charging his ultimate so it doesn't destroy the team). In a big gank, Rocket Jump will let you repeatedly slow the enemy team, as the cooldown resets every time you get a kill/assist.

And get Black Cleaver on her to increase your entire team's damage.

well... janna's knockback isn't AWESOME, but it's rather nice, as it means melee heroes have to reengage, and lose some time. besides that, her ulti [if she's even decently farmed] will essentially fully heal her team from 1/2 or 1/4 hp.
so... yeah >.> it's not bad.
Also, you're entirely wrong about nunu :] if you disable his ulti, it still goes off, albeit for less damage. Also, he can cancel it whenever he wants, and still deal the damage. It deals LESS damage, but the damage still isn't half bad.