>>52151414all you need is about 3 badges to catch and start using pretty much every single new pokemon. the ones that are pretty much late game only though are the sushi and sushi master and the other fish pokemon, the bisharp evo, and gholdengo (depending how autistic you get with hunting down coins you can maybe get it more early, but if you're not caring that much then he's definitely going to be around the end)
you can breed the 3 fish pokemon if you really want them early, again you'll need shit tons of luck and pokeballs to even catch them though.
i mean i guess you can breed a bisharp and just power level up all the way to level 50 in order to take the down the other level 50 bisharp you need, but at that point you might as just wait till you're naturally already around that time because then that's your highest level pokemon and the rest are probably in their 20s still.