>>33409203I used Cacturne. A little tough to get going at first but pretty good once you get to the water routes, especially if it has Water Absorb.
Pic related is my suggestion. It's not an absolute chore to find like in SM and it's at its best here. Castform got Hurricane in ORAS, so it can have Rain Dance, Weather Ball, Thunder, and Hurricane for a great rain set alongside already decent Sunny Day+Solarbeam. Furthermore, the best part about it is reusable TMs means you can switch between sets on the fly. I switched from Rain Dance+Thunder vs Glacia to a Hail set for Drake during the elite four. Plus, having a team member give you access to the thunder cloud felt great instead of just shoehorning Castform onto a team to make it appear. You can also give it an O-Power boost like Speed if you're not confident it can power through an important battle.
Overall, I'd say use a team of not-so-great pokemon plus your starter for a solid backbone to make up for ORAS being a tad easy.