you can use +blaziken or infernape or cinderace or greninja's or any starter they are good simple woobat which can be available in sewers is very useful for first few gyms
there some side quest look out for them and enjoy the game i like the story and if u want to be a good person and get relationship points there is a guide https://www.rebornevo.com/forums/topic/56219-rejuvenation-relationship-guide-v13/ link so dont get spoiled if you dont want to just be careful sites want any help ask again
edit :the one name i mentioned are good the starters some mightbe bad some might be good charizard depending on can be dangerous i done an flying mono and it very unexpected ability in certain fields actually u can battle specal terrains called fields depending on field pokemon gets nerfed or boosted with abilities and there movesets if u dont know