As the resident Hell Smasher, Zysa’s primary function is surgical extraction of problem individuals on the enemy team with a well-placed fist.
She loses some strength in exchange for Ki power and utility when Fused, but these idiots probably need it.
Fusing with Granyu gets her Healing Shout and... not much more, but it’s a pretty damn compelling argument. It’s how I originally found her; I was actually trying to get Granyu to another Fusion as a healer but found Heavy Smash to be just way too much fun. She’s also got a psychotically happy smile while using it in this form and that’s hilarious in conjunction with the Utter Horror on the face of whoever’s on the receiving end.
Fusing with Halda means a one-time revive on KO (which she hasn’t had to use yet) and a single-person, one-time Heal (in the form of Heal Power EX), which is usually enough to keep Futoh/Estoh out of trouble. She also gets Ultra Spirit Bomb, which is a nice “this fight has officially taken too long” nuke.