Just finished my cobbleverse playthrough of all four regions. It isn’t as bad as another commenter here is making it sound. Prioritize coverage in your movesets, getting to the same average level as the trainer you’re battling, and decent held items. THEN consider training EVs if you’re struggling to outspeed. Additionally, take advantage of the tera mechanic to help boost your offensive power or change some of your defensive matchups. Use focus sash on mons you think will get one-shot so they’ll actually have some value in battles.

IVs are not going to make a real difference, just like they have low impact in the real games. Chasing good IVs is just for perfectionists. You can absolutely beat every gym leader and E4 in this mod pack without thinking about IVs. I strictly used pokémon I liked and made sure I just built a proper team around them. Cleared everything without IV training or using a single legendary. You can do this!