Cloud Pirates

Flying
Cloud Pirates can block only creatures with flying.

Siren Stormtamer

Flying
{U}, Sacrifice Siren Stormtamer: Counter target spell or ability that targets you or a creature you control.

Impulsive Pilferer

When Impulsive Pilferer dies, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Encore {3}{R} ({3}{R}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Captain Storm, Cosmium Raider

Whenever an artifact enters the battlefield under your control, put a +1/+1 counter on target Pirate you control.

Captain Vargus Wrath

Whenever Captain Vargus Wrath attacks, Pirates you control get +1/+1 until end of turn for each time you've cast a commander from the command zone this game.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.

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.")

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.)