I tried

Voltareon2012

https://community.pokemon.com/en-us/discussion/comment/182691#Comment_182691

(how this challenge even work in Arceus there are no Pokémon centers)
Alright then do Shield. Your rules-
No using Pokémon Center healing.
If an NPC offers to heal your Pokémon, you can ONCE.
No buying things from stores.
No accessing your boxes.
Any Pokémon that you put on your team stays on your team until the credits scroll.
No Flying Taxis.