I'm a Rank 10, and it makes me think almost no one makes it that high because the battle for that rank was fucking ridiculous. One battle against a dude with a random uninspiring team of OUs, and then six straight battles with the same bloody combo against the same exact person, a Lady "Yay, a Farfetch'd! Weak!"
Tyranitar @ Focus Sash
-Stone Edge
-Earthquake
-Fire Blast
-Counter
Cresselia @ Brightpowder
-Swagger
-Toxic
-Double Team
-Moonlight
Suicune @ Leftovers
-Surf
-Swagger
-Sleep Talk
-Rest
ANNOYING. Needless to say I learned my lesson after the first battle and after disposing of Tyranitar with Garchomp, I let Breloom destroy the both of them easily.
Honestly, it's not very fun at all. Too many Garchomps, too many Weaviles, Milotics, Togekisses, etc. It's all the AI hax but minus the crappy GameFreak-generated pokes.
If you ever make it to Rank 10, play room 1 and see if you face me.
The only things that made me rip out my hair were Scarfed Togekisses, but then I learned to avoid particular rooms and never encountered them again. Suicune with Pressure was an insanely invaluable asset and made a joke out of the innumerable Milotics I faced. Battles were time consuming as all hell, but I didn't mind pressuring things to struggle mode if it meant winning. Then again, occasionally the faggot CPU would get a crit + status and/or stat down and if not losing I'd win by the skin of my teeth. As for surprisingly effective, once and only once I fought a Curse+Payback Umbreon that gave me a run for my money.