>>30176733You probably just suck. I ran fucking monotype and only had problems with a trials and the Champ.
As you play through the game, take note of whichever 'mons give you trouble and come up with some way to deal with them. Make sure each of your 'mons has a STAB move for each of its types, plus a coverage and utility move.
Don't just slap a bunch of moves on your 'mons and call it a day, look at what they're good at, play to their strengths and form a strategy. My Drifblim, for example, plays by putting a Toxic on the guy and then using Fly/Phantom Force to stall for time while my Trevenant uses a combination of Leech Seed and Horn Leech to re-heal all but super-effective hits.
Try to synergize between 'mons. For example, Toxapex, Cloyster and Tentacruel learn Toxic Spikes, while Hex and Venoshock shoot up to 130 Base Power if the target is poisoned.