>>49537260i have literally zero tips but probably try to do as little exploration as possible. catching a ton of pokemon is sort of the main exp gain in this game so i'd say just regularly swap your team out with alphas. Just keep trying to catch alphas, or exceptionally high level pokemon.
For example in the Obsidian Fieldlands before you even battle Mai you can catch Dustox/Beautifly in their early level 20s, they're by that farm area to the left of the camp, they're is much better than all the other mons at like 10s at most. Or maybe even grab that alpha luxio or snorlax if you can (i forget if snorlax is reachable before Wyrdeer but i think it is?) You'd need to just get lucky with a pokeball/heavyball, which may be more trouble than it's worth. I'd recommend trying to passively increase your star rank as well, maybe just chuck a pokeball at passing 'mons without getting distracted just to get the points. Playing through the whole game while needing to constantly catch strong pokemon without some decent pokeball types sounds hard. So yeah, basically don't have a consistent team, leveling them up is a big time loss and the game gives you enough high level pokemon relative to each area that you could just continuously swap em out.