Gemcutter Buccaneer

Whenever Gemcutter Buccaneer or another Pirate enters the battlefield under your control, create a tapped Treasure token.
Treasures you control are Equipment in addition to their other types and have "Equipped creature gets +2/+0," equip Pirate {1}, and equip {3}.

Francisco, Fowl Marauder

Flying
Francisco, Fowl Marauder can't block.
Whenever one or more Pirates you control deal damage to a player, Francisco explores.
Partner (You can have two commanders if both have partner.)

Skeleton Crew

Each other creature you control that's a Skeleton or Pirate gets +1/+1.
Whenever one or more creature cards leave your graveyard, create a 2/2 black Skeleton Pirate creature token. (This ability triggers only from the battlefield.)
{5}{B}: Return Skeleton Crew from your graveyard to the battlefield tapped.

The Indomitable

Trample
Whenever a creature you control deals combat damage to a player, draw a card.
Crew 3
You may cast The Indomitable from your graveyard as long as you control three or more tapped Pirates and/or Vehicles.

Admiral Brass, Unsinkable

When Admiral Brass, Unsinkable enters the battlefield, mill four cards.
At the beginning of combat on your turn, you may return target Pirate creature card from your graveyard to the battlefield with a finality counter on it. It has base power and toughness 4/4. It gains haste until end of turn. (If a creature with a finality counter on it would die, exile it instead.)