Malcolm, Keen-Eyed Navigator

Mana cost: {2}{U}
Type: Legendary Creature — Siren Pirate
Power / toughness: 2 / 2
Set: Commander Legends #560 (uncommon)

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 token: Add one mana of any color.")
Partner (You can have two commanders if both have partner.)

Malcolm, Keen-Eyed Navigator has 5 printings, first in Commander Legends (2020). EDHREC ranks it #3,250 among Commander cards. It appears most in Edward Kenway decks (10,151 on EDHREC). 1 public deck on TCG runs it. It has 9 official rulings.

Legality

commander: legal
legacy: legal
vintage: legal
pauper: not legal
modern: not legal
pioneer: not legal
standard: not legal
brawl: not legal

Public decks that run Malcolm, Keen-Eyed Navigator

Ahoy Mateys - The Lost Caverns of Ixalan Commander, led by Admiral Brass, Unsinkable

Commanders that run Malcolm, Keen-Eyed Navigator most

Deck counts from EDHREC.

Edward Kenway: 10,151 decks
Admiral Brass, Unsinkable: 7,330 decks
Don Andres, the Renegade: 4,527 decks
Captain Howler, Sea Scourge: 4,460 decks
Admiral Beckett Brass: 4,031 decks
Mary Read and Anne Bonny: 901 decks
Captain Storm, Cosmium Raider: 833 decks
Ramirez DePietro, Pillager: 403 decks

Often played with Malcolm, Keen-Eyed Navigator

Cards that show up in the same decks on EDHREC.

Rulings

2020-11-10: Both commanders start in the command zone, and the remaining 98 cards (or 58 cards in a Commander Draft game) of your deck are shuffled to become your library.
2020-11-10: Malcolm's triggered ability will trigger even if Pirates you control deal damage to only a single opponent. A single Treasure for you. Yarrr.
2020-11-10: To have two commanders, both must have the partner ability as the game begins. Losing the ability during the game doesn't cause either to cease to be your commander.
2020-11-10: If your Commander deck has two commanders, you can only include cards whose own color identities are also found in your commanders' combined color identities. If Falthis and Kediss are your commanders, your deck may contain cards with black and/or red in their color identity, but not cards with green, white, or blue.
2020-11-10: An effect that checks whether you control your commander is satisfied if you control one or both of your two commanders.
2020-11-10: You can choose two commanders with partner that are the same color or colors. In Commander Draft, you can even choose two of the same commander with partner if you drafted them. If you do this, make sure you keep the number of times you've cast each from the command zone clear for "commander tax" purposes.
2020-11-10: Once the game begins, your two commanders are tracked separately. If you cast one, you won't have to pay an additional {2} the first time you cast the other. A player loses the game after having been dealt 21 damage from any one of them, not from both of them combined.
2020-11-10: If something refers to your commander while you have two commanders, it refers to one of them of your choice. If you are instructed to perform an action on your commander (e.g. put it from the command zone into your hand due to Command Beacon), you choose one of your commanders at the time the effect happens.
2020-11-10: Malcolm's triggered ability considers all damage dealt by Pirates you control to opponents, not just combat damage.