I had my worst lag on Pokemon Stadium 2, although that was probably down to the connection at the time. 'Twas quite funny however, after about 5 minutes of extremely slow movement, hearing a perfectly clear "GULPIN" above the now annoyingly repetitive Pokemon Center music.
On a more useful note, Distant Planet is supposed to have the worst lag, and I've had some pretty slow battles on Delfino Plaza.
THAT WAS THE BEST ONLINE MATCH EVER!
And we could see Gulpin on the screen for about 2 minutes before he actually spoke.#
But ye, it is the stages that have fancy backgrounds and big obstacles. Rainbow ride should be fine, shouldn't it?