Scythe! Because you know, Scythes are awesome!!!! Long range sweet spotting similar to Marth but much harder to perform, probably slower but harder hitting. Focus would be on hitting enemies with the long handle or thrusting it forward for incredibly weak damage, and using the slow powerful Scythe Blade attacks to punish those that don't space themselves properly from you... Yes???....... No?...... okay...... *hides in a corner*
Realisticly Magic is probably a likely one (probably with a wand or staff as well). A shield user might be likely too. Though it'll probably have a mace/sword, as it's incredibly rare for characters to only use shields as weapons.
A spear/polearm is the only other one I can think of, but even that's pushing it. As for anything else, usually they aren't popular enough, or it's too similar to the styles we already have in game.