I'm not sure how interested /vr/ is in this, but I'm sure you guys have watched the last couple of GDQs. If you remember the super jump and jumproll glitches, it was recently found that you could perform both at the same time, giving speedrunners the ability to roll over stages. I'll make a video in a bit, but you can find my stream in the DKC section of Twitch if you want to come check it out.
Where do no percentage requirement speedrunners draw the line? If holding a certain button combo at startup allows you to warp straight to the ending, would that become the preferred way to "speedrun" said game?
Well, not quite. Speedrunners also take entertainment into account, and just being able to hold a button combo to beat a game would be trivially easy, not much fun to watch, and not much fun to compete with others either.
In cases where a super-fast skip exists, there's pretty much always a separate category that disallows use of that glitch.
All the categories are technically arbitrary, but they're not chosen stupidly.
It would be valid, but what would likely happen is that people would name that the XYZ glitch and people would start doing "any% no XYZ" runs of that game.
You can see a less extreme example of this with Ocarina of Time. There's a warping glitch that lets you beat the game in about 18 minutes, and this is what people use if they're going for the world record, but people still do lots of runs of other categories like all dungeons or all medallions.
Earthbound has a glitch pretty similar to what you describe where you can warp straight to the credits. It might be TAS only though, I don't remember.
People were discovering new glitches in Super Metroid as late as two years ago. The best times for Mario 64 and Ocarina of Time continue to be improved, long after people thought those games were completely solved. It's amazing what you can do in these games.
Yeah, because I have at least one development copy of a game that lets you skip straight to the credits from the opening menu. Since some seem to allow variations of the game for speed purposes (like the iQue OoT), I guess I could easily hold the world record any % for those games. Cool!
That's a common thing, actually.