*Guzma had become the Pokémon Professor in Alola together with Kukui, but he wasn't there at the time.

Guzma was therefore alone in Kukui's house waiting for him to return, let's say that Guzma wasn't the good one with pokémon.

he did subspecies of experiments on pokémon when he was alone. while Kukui was away he was actually doing one...

but you come in having the keys because you were supposed to meet Kukui,and you catch him instantly with wide eyes and Guzma did the same