I finally beat all the challenges. For me, the evasion took me the longest time, but I eventually got it since I just kept on trying. It turns out that if you go in a circle and keep on changing the destination, the opponents have to keep changing THEIR direction, too - they get confused after awhile, I think...
None of the other ones were hard in their execution - it's just finding the right strategy for each that's the hard part...
Hey Pseudolonewolf, have you also changed the requirements for the ranks along with your changes to the rooms? Because just that one change in 1_8 adds at least 20-30 seconds to one's time, and as I'm sure you've noticed, that's enough of a discrepancy to displace several players who've finished JUST in time from their "S" rank... O_o
If he did that, then it wouldn't be like the old-school experience at all. In the original super mario bros. there wasn't a save function! O_o Then again, I'm not saying I would mind if he added one...
 "Bot Arena 3"){kind=icon}
 "Raider: Episode 1"){kind=icon}