The fastest pirate costume is not always the busiest one. What matters first is silhouette. A long coat, loose shirt, sash, vest, boots, wide belt, or head scarf can say pirate before any accessory joins the crew. The shape tells the eye where it has landed.
Next comes contrast. Pirates in popular imagination live in strong visual opposites: dark coats with bright sashes, rough shirts with shiny buckles, practical boots with theatrical hats. A costume that mixes texture and contrast usually reads better than one that is perfectly tidy.
Then choose one loud detail. It might be a hat, bandanna, belt, hook, eye patch, toy spyglass, striped socks, or a piece of jewelry. One good detail gives people something to remember. Six random details can start arguing with each other.
For groups, vary the roles. One captain, one deckhand, one fancy rogue, one tiny menace. The costumes will look more interesting together, and nobody has to compete for the exact same hat. That is how a crowd becomes a crew.