In my HeartGold, and my very first actual attempt at the Battle Tower, I decided to try a little Baton Passing. It isn't working very well, just for the record. Full team:
I just really like the Nincada family and I thought I'd use Pokémon I like and an original enough strategy. (Garchomp is kind of like a super mutated Nincada, right?) I'm actually probably going to make a team with Ninjask, Nincada, and Shedinja next, but that's not the point. Okay, here's how it went, and I believe it was around battle 16, and I didn't record it because I was pissed.
I sent out Ninjask, they sent out Seaking. (I figure at this point I will use Substitute instead of Protect while they use Rain Dance so I can work from there)
Seaking outsped my Ninjask and used Aqua Tail, and knocked by Ninjask down to about 17% health, then I fail to use Substitute. (Okay what the hell, it must be a Choice Scarf, because there's no Rain. Now I'll boost my Speed as much as possible and Baton Pass to Shedinja who will wall this Seaking)
Ninjask used Protect, Seaking used Aqua Tail. (Now my Ninjask is +2 thanks to Speed Boost, so I'll Baton Pass)
Seaking used Poison Jab! And obviously killed my +2 Ninjask before I could Baton Pass.
Seaking can't learn Aqua Tail in the Battle Tower movesets from what I've seen, but back to the battle.
I got really pissed and distracted at this point so I wouldn't break my DS, and it seems that the Seaking outsped and killed my Garchomp and Shedinja with Horn Drill and Peck respectively. Sorry I don't know more about the last part, but I could bet my life on the part about the Seaking outspeeding and killing my eventually +2 Ninjask without Rain Dance or a Choice Scarf