I looked into it, a fighting game.
Yeah, Laharl would be perfect. Actually sometime back I tried to come up with how to do a NIS based fighting game with characters from various games (originally was thinking something Dragon Ball Z like, but after a while realized that the 2-D style worked better).
Laharl was one of the easier ones to work into the idea.
(For characters of different games using the same weapons, I figured that some specials and combo moves would relate to their specific game's incarnation).
As such I figured Laharl with a sword, would have
Blade Rush (Special): a dash attack where you press P again when you get close to the opponent to perform the slash move instead of just dashing past them (to relate it to the animation from D1, and help differentiate it from what I would give Mao, and now Valvatorez).
Hurricane Slash (special throw)
Air Slicer (Special: Air only)
Blazing Knuckle (Special)
Overlord's Wrath (Hyper move)
Meteor Strike (Hyper move)
Naturally more specials and one more hyper move would need to added *it would help if unique characters had more than three moves* thanks to the DLC of Adell, Rozalin, and Mao I can now come up with full movesets for them, Flonne too now has three hypers, her three strongest moves from the past, that Final Beam or what ever from D1, Flonnezilla, and now Flonzor-X. Where her Hearts/Feathers is a special move. I'd also give her some arrow moves, but only because I always equip her with an arrow weapon instead of the staff (the anime kind of did too a little).
Apparently given Trinity Universe and Cross-Edge I was not alone on the idea of giving Etna some spear moves to even her out.
But on topic; yes Laharl would be both easy to impliment and help diversify the roster.
I mean heck Smashbros had tons of Obscure characters (including some that were only in Japan), and the Vs series from Capcom loves to throw everyone into the fray they can.
(At this point Morrigan Aensland is more famous for being the Vs series than for being in Darkstalkers).
Good? Evil? I am what I am; a force of nature.
Overlord? Diety? I wasn't aware I was in charge, I am just the creator.