So, I've been playing Final Fantasy X again lately (one of my favorite games of all time). I'm doing the insanely-ridiculous
NSGNSNCNONENNENBB challenge. I've previously done it minus the NENNENBB part, and I'm currently up to where I got to on that eventually-abandoned attempt; just after Macalania Temple. Have to repeatedly try fighting Wendigo until it drops an SOS Haste armor for Rikku; although the challenge is possible without one at this point (and one can be obtained much easier later), I think I'd rather farm Wendigo for one now than go without one until much closer to the end of the game.
I've also been a bit stricter on the No "No Encounters" part of the challenge than most players usually are. Generally, it's taken to just refer to literally having an armor (or weapon) with the No Encounters auto-ability, but I've also interpreted it as not doing anything else that actively prevents random encounters, such as activating the butterfly minigame in Macalania Woods, or riding a chocobo (unless it's for the explicit purpose of getting to somewhere you can't reach without riding one).
I've done some fairly insane challenge runs before, but this one is really in a league of its own... wow.