Headcannon: Solgaleo and Lunala's diets consist largely of a substance very close to that of sugar and their bodies burn through it rather quickly. To put it in simple terms they like sugary foods and need to eat something sugary everyone once and a while or they go crazy.

Nebby flies around the place acting as she was on something. Zekrom and Kyurem just stand there, arguing.

Zekrom: What did you give her?

Kyurem: ....

Zekrom: Well you did something and now she's not acting right!

Leo comes into the room and looks horrified. The Lion Pokémon tosses a few sugar stars to Nebby. She eats them and calms down.

Leo glares at the two.

Leo: Did you two forget to give her something sugary!? She was going into shock!