Pokémon

The trick is to plan from the start by keeping some zigzagoons in your team for their pickups. They will sometimes grab rare candies as well as potions quite often, and they also are good HM... helpers. If you don't like to grind, you can "upgrade" them around Fourtree City, where they spawn at higher levels, improving the pickup items. Hold every rare candy you get until you reach the league and your pokes are leveled, so they grant more experience. Ik you are already past the point of this being helpful for your current run, but this is for the future or anyone else reading.

Edit: catch Rayquaza (lv.70)

I usually just spend all of my money and farm directly the elite fours.

You go in, kill some pokemons and die. Rinse and repeat.

There’s a loop you can do fighting the interviewer and cameraman. It takes a few times beating them before their team levels up, but it’s relatively quick exp due to it being two higher-level, evolved mons in a double battle.

If you put exp share on a mon that is out in the battle, it gets a higher share of the battle xp so long as it doesn’t faint. I did this to level most of my mons for the living dex.