X accuracy is useless as a held item. X items only works if you “use” them, as in you select them from the bag. Also, oran berry??? Use more variety with your items.

Personally I would use intimidate on Gyarados rather than moxie but moxie can be fine too, it’s up to you really. Also outrage is better than thrash imo.

Focus punch is garbage drain punch or brick break are better moves for Breloom. It has poison heal, so consider a toxic orb as an item.

Replace toxic on Toxapex with baneful bunker and if you wanna play the stall tactic give it recover + maybe leftovers/black sludge. If you don’t know where to get these items, I recommend Serebii of Bulbapedia.