Any recommendations for Battle Subway teams (single or double), or any basic tips as to what you can abuse against the AI this time around? I just want to be able to get to the 49 win mark quickly and consistently. My 4th gen teams aren't cutting it that well for this since the early rounds use decent Pokemon now.
I find doubles to be the easier and well.. more entertaining mode of play. I usually abuse Sand Stream (and thus, Excadrill), or Politoed with Drizzle and Swift Swim Pokemon. The AI can't really fight weather easily, but they will try to throw teams at you if you have a lot of common type weaknesses.
Don't use moves with low accuracy either. Rock Slide is acceptable, if only because so many Pokemon receive it and the chance to flinch is great in Doubles. But it will screw you once in a while. Put Protect on almost everything. It'll help you scout, it'll help you keep someone up and you finish the threatening Pokemon with your second.
Don't use Choice items, for the most part. Although having a Choice Scarf in the back can be handy to finish off, it could cost you. The type-boosting Gems are great, and allow things like Dragon Gem boosted Outrage to destroy everything. Trick Room / Gravity / Tail Wind can work, but I find them more unreliable than weather because they require a turn to setup and they can be stalled out (and AI will use stalling methods sometimes).
And in case you play singles, Trick-trapping doesn't work anymore. In Gen IV you could Trick a Choice item on to a Pokemon that used a non-damaging move. The Pokemon would just stay in and let your Pokemon setup. Now the AI will switch their Pokemon. So, Trick can be handy to have, it's not that great anymore.
Places like Smogon have a list of all trainers in the subway, so you can look at movesets for Pokemon and trainers and know what to expect. Really, unless you're aiming for a 200+ mark, you probably don't need to study like that.