Had this idea for a long while now for Kukui's Rarer Candy form. "But it should have been Incineroar, it's such an obvious choice!", I hear you shouting (Nah, that'd be too predictable, you aren't predictable... are you?). Well, lemme explain the reasoning behind this.

1. One of the largest aspects of Kukui is his fascination with attacks. He studies them, he battles to see them, and he takes them head on. Having him as a Wobbuffet lets him experience more attacks with less personal risk.

2. He likely used his first rarer candy (the one that establishes your form) as "Kukui", because using his first one in the ring as the Masked Royal would have been a risk if he turned into something he didn't know how to work with.

3. It opens more options for writing. Most likely, he would only use his pokemon form as Kukui, OR the Masked Royal, not both, because that could give his identity away. Having it be "Kukui's form", suddenly means that the Masked Royal either doesn't have a pokemon form, or doesn't show it off. It allows for scenarios where, someone launches an attack at him, he quickly changes, deflects the attack, and as the smoke clears, he turns back, making people think that the Masked Royal is somehow taking on attacks in the ring without breaking a sweat.