Kallisto's gimmick would need a few tweaks if he were to be marketed as a heel on the main roster - he's currently holding the NXT Tag Team Championship alongside the decidedly babyface Sin Cara. With the exception of Sin Cara Negro (let's try and forget that ridiculous feud), luchadores are almost exclusively marketed as perma-babyfaces by the WWE. Rey Mysterio is one of the few superstars never to have turned heel in the WWE, despite his experience working as a bad guy in the WCW's Filthy Animals stable. A heel luchador would be a breath of fresh air to modern American wrestling. If Kalisto were to drop his current brightly-coloured attire and go back to a look similar to the one above, he could certainly make it work. A simple way of introducing him would be to bring him in with a returning Sin Cara, only for the newcomer to turn on his partner within a few weeks and put him out of action. https://www.youtube.com/watch?v=oQ1lGPNZNBU
