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Oh hey! I remember you 10 years ago from Pokéland :D
To actually answer your question, Cherrim did greater than I expected. Raising Groudon's Atk and SAtk stats + Helping Hand. Also giving me some advantage turns with its Protect barrier. Too bad it can't do anything when all its partners are...
My team is in the attached image.
It was fun, but playing all the 30 battles in 1 day is harsh. I did 23 - 6, I'm not sure what happened to my last battle, since it disconnected a few minutes after midnight. Most of my defeats were in the last battles, so maybe I got tired in the end. I thought...
As I'm finishing college final paper thesis and working full time, I could only think abou this competition on Sunday. Then I read this whole thread to have an idea of what to expect and what to use on my team. I could only play 21 battles, 16 wins & 5 loses. I didn't expect to go this well, but...
Falkner can cause too much headache if you're raising bug pokémon at the beginning, but also way too easy if you've been raising Cyndaquil or Totodile.
I always liked Johto the most, but the best region environment is Hoenn. It also atches with the story, which is so far, in my opinion, the best story in the game series.
(Except for Orre, I haven't played Colosseum or XD, so I can't judge them).