The siblings control the Skynoah, a ship that was based on their father's Blacknoah. The siblings were the hosts of The King of Fighters 2003. Rose watched Adel fight while playing the piano but he was defeated by the Ikari Warriors team (according to the manual, he was defeated by K', Maxima and Whip). She didn't want to release the winners, but Adel's sportsmanship told her to release them, since they won fair and square.
The next tournament, she joins Adel in his search for strong fighters and once again the hosts of the XI tournament. She eventually stops his battles just to speak with her brother or taunt his enemy. She is actually being controlled by Botan to host this tournament and is still under her sway to host the XIII tournament.
She does not fight, but she does a little bit of unused fencing arts in-game.