I'm a bit bothered on the usage of PK: although it's more well-known, what about PSI? Is it PK or PSI? I've seen a bunch of different explanations - most commonly, that PK was used in the original game and in SSB (the dubbers didn't bother to dub in "PSI") or that PK and PSI differentiate certain attacks...
Anyway, I prefer WikiBound, because it's...well I dunno. Just that PK doesn't always just apply to EarthBound. PK can be a ton of things, like "player kill" or "psychokinesis" outside of EarthBound.