If i can add my reccomendation: I seriously suggest giving Grookey a try. Why exactly?
Two words: Grassy Surge.
Having access to a 'mon that can just outright remove most annoying field effects since the start of the game can turn a lot of difficult battles into a cakewalk. (Looking at you, Valarie. And at you too, Angie. And don't think i forgot about you, Saki.)
Rillaboom also hits like a truck, and gets access to a lot of strong moves like Wood Hammer and Knock Off just by levelling.
For comparison's sage: The only other 'mons that have access to the Surge abilities (other than the Tapus, who we obviously won't be getting for a long while) Are Indeedee, Pincurchin and Galarian Weezing. The only one i could find so far is Indeedee (Can be gotten in Chapter 9), and i still found myself using Rillaboom anyway due to its' sky-high attack and amazing synergy with the Grassy Field.
Also: Its' Rejuv custom shiny is themed after Donkey Kong. You can't top that.
So yeah, give Grookey a shot. It opens up a lot of different strategies on how to approach certain fights just by having access to Grassy Surge since the start of the game.