Is it bad if I don't have a poipole yet
Apparently you're supposed to find one on Day 17 in a small room near the classroom. Maybe post-game stuff will have a way of getting Alolan legendaries and mythicals you missed.
I found another trainer I don't know the location for: Virgil.
Is Misty's Rematch team the same as the team she uses in Driftveil? She doesn't have a separate Driftveil team.
I've got the guide:
https://docs.google.com/document/d/1sRMak0uV1lYK755zt5DF0fVenFxeOc6nl5nsOrSm0-o/edit?usp=sharing
Region order:
Kanto (Indigo Plateau)
Orange Islands
Johto
Hoenn
Kanto (Battle Frontier)
Sinnoh
Unova
Kalos
Rematches and Ash Fights
Alola (Uses version 2.10 walkthrough)
Driftveil Battle House (Will start once Alola is finished)
Includes: Gym Leaders, Elite Four, Champions, Frontier Brains, Trial Masters, Totem Pokémon, Traveling Companions, Rivals, Team Rocket (JJM), Evil Team Leaders, League Participants, Club Battle Participants*, Whirl Islands Participants* and various others.
Club Battle and Whirl Island Participants are included because one or more of Ash's rivals/friends participated in them.
Various others includes: Hobbes, Ash and Doug (Only Kanto and Kalos fights so far for Doug)