Meh.
I might enjoy Triple Battles if I were to assemble teams for them, but just thrown in here and there like they are, I don't, and in fact actively dislike them. Battles with multiple pokemon rely on a few strategies that are different from single battles, and since the vast majority of the battles in the game are single, that's what my teams are designed for. They don't sync well for multiple battles, though they can generally get by in doubles. In triples though, it's most obvious that they don't sync well, so they just end up being annoying.
Rotational battles are fun with other people, but they're sort of pointless against the AI. With other people, you get into some complex strategy, since you're trying to predict the other person but also aware that s/he's trying to predict you, so maybe rather than choosing based on what you think the other person is going to do, you need to choose based on what you think the other person thinks you're going to do, and so on. It can get very involved. But since the AI is dumb as dirt, there's very little of that. It doesn't use sensible strategy, so there's little on which to base any predictions, and pretty much all you can do is try to use a pokemon who can weather all the opponents' attacks and go for a sweep, which is sort of dull.