You know, you could have ripped off Omega's Ranbu for the Final Smash...
Anyways, I've been trying to think up a decent move set for this character for quite a while, and I think I've got it. We all know that Fire Emblem has more than swords to offer. Save the axes, lances, and tomes, I'm going for claws. This particular cat has a tongue that cuts just as deep. She's tough as nails, but still cute enough to woo the enemy into swallowing some laced food should the need arise. And she's probably the only person besides Mia who actually enjoys sparring with Ike:
Lethe (Fire Emblem: Path of Radiance; Fire Emblem: Radiant Dawn)
*normal form*
Very fast and evasive, but weak in both damage and knockback.
B - Counter. Doesn't work against projectiles. If struck by a melee attack, Lethe blocks it and gives her attacker a boot to the head. Good distance, low trajectory, little damage.
Smash B - Pass. Lethe dashes forward. If she hits an enemy, she'll kick them behind her.
Up B - Smite. Lethe leaps into the air, and if she hits an enemy, automatically head-stomps them. Does no actual damage. Does not leave Lethe helpless, and may be repeated after a successful hit.
Down B - Shift.

*shifted form*
Powerful, heavy, and reasonably quick, but also a large target and suffers "stamina" slowdown if maintained over 2 minutes.
B - Roar. Lethe lets loose a roar that stuns nearby grounded enemies.
Smash B - Quick Claw. Lethe tenses up. If struck by a projectile, she leaps towards the owner and delivers a powerful blow.
Up B - Resolve. Lethe leaps into the air, and if she catches an airborn enemy, will grab them and drag them down to the ground.
Down B - Revert.
Final Smash - Rend. Lethe shifts if she hasn't already, roars to stun and slightly damage all foes, and rushes forward. If she catches an enemy, she unleashes a furious combo of fangs and claws finished with a somersaulting blow that launches her opponent.