Final Fantasy, Kingdom Hearts, Legend of Zelda, Super Mario, Sonic, Metroid, Pokemon, MegaMan, Street Fighter, DarkStalkers, Dragon Age, Tales of Series, Metal Gear, just about anything related to those series, & any other games that catch my interest.
Yeah, you have to fight him 3 times, after the third is when you get him. You can also get Flonne. Same goes for all three in Disgaea 3.
Laharl even gets an Anime cutscene in 2.