Can you honestly blame him?
Can anyone remember if, in Pokemon Yellow, Pikachu had to get in his Pokeball to heal the the Pokemon Center?
No, he didn’t. They even changed the counter design to allow for it.
Actually, while they never showed him getting in the Pokeball, it then showed you six Pokeballs in the healing device. Then Nurse Joy turned back to the back and handed you Pikachu.
Actually, Pikachu just jumped up on the machine. In other words, it appears that a small enough pokémon wouldn’t have to get in the pokéball to be healed.
Offer him a Friend Ball instead. Admittedly if he’s holding out for a Luxury Ball he’s just being picky.
Masterball surely, there is only one of them. It’s like saying, I choose you
Of course they’re gonna use the rarest object in the world on a disgruntled customer.