Arcane Adaptation

As Arcane Adaptation enters, choose a creature type.
Creatures you control are the chosen type in addition to their other types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

Malcolm, Keen-Eyed Navigator

Flying
Whenever one or more Pirates you control deal damage to your opponents, you create a Treasure token for each opponent dealt damage. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Partner (You can have two commanders if both have partner.)

Conspiracy

As Conspiracy enters, choose a creature type.
Creatures you control are the chosen type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

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.)

Vial Smasher, Gleeful Grenadier

Whenever another outlaw you control enters, Vial Smasher, Gleeful Grenadier deals 1 damage to target opponent. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Imagecrafter

{T}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Unnatural Selection

{1}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Ramirez DePietro, Pillager

When Ramirez DePietro, Pillager enters, you lose 2 life and create two Treasure tokens.
Whenever one or more Pirates you control deal combat damage to a player, exile the top card of that player's library. You may cast that card for as long as it remains exiled.

Rukarumel, Biologist

As Rukarumel, Biologist enters, choose a creature type.
Slivers you control and nontoken creatures you control are the chosen type in addition to their other creature types. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 1/1 colorless Sliver creature token.

Mistform Wakecaster

Flying
{1}: Mistform Wakecaster becomes the creature type of your choice until end of turn.
{2}{U}{U}, {T}: Choose a creature type. Each creature you control becomes that type until end of turn.

Breeches, Brazen Plunderer

Menace
Whenever one or more Pirates you control deal damage to your opponents, exile the top card of each of those opponents' libraries. You may play those cards this turn, and you may spend mana as though it were mana of any color to cast those spells.
Partner (You can have two commanders if both have partner.)

Xenograft

As Xenograft enters, choose a creature type.
Each creature you control is the chosen type in addition to its other types.