After Plumeria's notion how Lillie is similar to Lusamine, I just realized relationship of Guzma and Lusamine is actually a darker parallel of MC and Lillie's. While it is more pronounced with male MC, female MC does have same role,dialogue and also same implication.
Both you and Guzma are vehicle of Lillie/Lusamine's objective. And both you mostly get paid with nothing but lip services.(Guzma probably got some team skull funding too, but Lillie did gifted you with 5 luxury balls...)
The one who went into UB world with Lillie is not Gladion or Hau but you, like how Guzma went with Lusamine instead of Faba or other Aether grunts. In the end Lusamine sort of ditched him for UB while Lillie left you and went to Kanto.
Other similarity including how Guzma was also a trial-goer in his youth and a competitive-focus trainer, like you. Though Kukui and Molyne has similar background, they seem to have grew up and choose occupation as researcher/programmer instead while Guzma stuck in the phase of "being the strongest trainer/beating everyone"

tl,dr Guzma is your evil counterpart