I may be a bit late in discovering this, but you can become Gigalypuff on Pirate Ship

When the ship is approaching the rock, jump on it, and use your final smash. When you hit the damaging part of the ship, you'll cancel the FS and stay big. It's much more fun on Pirate Ship, because you can't kill yourself by f-smashing or rolling. It's also much easier to corner people.

Just don't fall in the water, because jumping out kills you. The cannon still has enough knockback to kill you, so try to dodge to cannonballs with rolls or something. Also, try not to become too big, or the bottom of the ship will hit you even when you're on top.

Never knew o.O.