The "level" that I had the most trouble with, in any Mario game, is Flipsville Galaxy's Green Star 3 in Galaxy 2. I probably spent over 30 lives trying to land on the damn star.
I don't remember having any trouble with The Perfect Run, though. I even liked it! Maybe I'm just lucky?
I also remember having trouble with Tubular when I was younger, but I can't remember to which extent.
Originally posted by NimonoWhich one's Outrageous?
It's the Special World level with Wigglers, Bullet Bills and Hoppin' Flames. It's in a forest and requires you to use a Springboard once or twice.