KOF 2003 features a diverse roster of characters from various KOF series, including iconic fighters like Kyo Kusanagi, Iori Yagami, and Mai Shiranui, among others. Players can choose from 40 fighters.

Special moves and combos can be executed by inputting specific button combinations during gameplay. Each character has unique moves, which can be found in the move list in the game's menu.

KOF 2003 introduces a '4-on-4' team system where players select a team of four characters. You can choose to switch characters mid-fight, providing a strategic advantage depending on the situation.

To unlock hidden characters in KOF 2003, you must complete specific challenges or achieve particular milestones in the game. This can include finishing the arcade mode on normal difficulty without continuing.

The Power Gauge in KOF 2003 allows players to charge their special moves and execute powerful techniques. It has three levels: 1) Build up by taking damage or dealing it, 2) Use it for specials, 3) Activate max mode for enhanced abilities.