Oh master zed, i was looking at your "challenges FAQ" on
www.gamefaqs.com this morning while playing, and i started a new game trying to go for severeal awards all in a single playthrough.
* Peacekeeper: Never kill enemies, only mid bosses and bosses - Sucess
* Mega Diet: I failed cause i accidently collected that one un-avoidable energy on wily 3.
My fault
* And well i thought i could get that one about beating 4 stages with the same weapon. I thought the only thing that mattered was just beating the bosses. I beat 4 with rush coil switched out only, didn't get it...beat the last 4 bosses with concrete weapon, still did not get the award.
I did not realize i was meant to play through the WHOLE stage(s) with the weapon switched out. I guess that was my fault again...but..
* 100% accuracy with Mega buster. I'm absolutely certain i only hit splash woman one time only, as the first boss i picked one time, then used rush coil for the rest of the game mostly. And i did not ever get the award.
I know your guide said rush coil is allowed, but ..it might NOT be.
So that was a failure.