Swamp

Plains

Sol Ring

Fathom Fleet Captain

Menace
Whenever Fathom Fleet Captain attacks, if you control another nontoken Pirate, you may pay {2}. If you do, create a 2/2 black Pirate creature token with menace.

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Dire Fleet Poisoner

Flash
Deathtouch
When Dire Fleet Poisoner enters, target attacking Pirate you control gets +1/+1 and gains deathtouch until end of turn.

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.)

Greedy Freebooter

When Greedy Freebooter dies, scry 1 and create a Treasure token. (To scry 1, look at the top card of your library. You may put that card on the bottom. A Treasure token is an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Forerunner of the Coalition

When Forerunner of the Coalition enters, you may search your library for a Pirate card, reveal it, then shuffle and put that card on top.
Whenever another Pirate you control enters, each opponent loses 1 life.