Twin Yo-Yos transforms the Keyblade into two blue, bladed yo-yos bearing the Monsters, Inc. logo. The "string" of the yo-yos is instead beams of light.
In Kingdom Hearts III, Twin Yo-Yos is the second Formchange of the Happy Gear Keyblade, associated with Strike Form and following Agile Claws. Its combos have Sora swing and throw the yo-yos around himself, often flipping around to strike multiple enemies at once and performing yo-yo tricks for finishers. Twin Yo-Yos uses Dual-style Magic.
The Finish command has Sora transform the yo-yos into two sets of teeth that clamp down on the enemy before biting down three times.
Learning Twin Yo-Yos
Kingdom Hearts III