I was wondering are the Pokemon of the trainers in battle subway preset or do they go off of the Pokemon you selected?

Question

im asking this because I made a mono fire team and it seemed like every trainer I battled against were useing all mono water until I was basicly defeated

Answer 1

It's more of random chance. You use three (or four in double battles) Pokemon, so when a Pokemon which is strong against one of yours shows up, some people are inclined to shout "OMG HAX." The trainers have pre-set Pokemon, which you can find on Serebii.
The trainers on the Battle Subway have different combinations
Here is the Serebi link

Hope this helps