@MyWy, in case you’re interested, I wondered a while back what exactly is the difference between captions and subtitles, and I learned the answer: Subtitles only include dialogue whereas captions include other stuff ([ominous music], [car engine starts], song lyrics, etc.).
Shout Factory has released 39 MST3K box sets to date, and about halfway through this run they started captioning the episodes. Each 4-disc set contains episodes from across the 10-season run, so the net result is that about half of all original episodes are captioned, roughly 50% from each season. (All season 11-12 episodes were subtitled from the start so I don’t include them here.)
It is hit-and-miss; some classic episodes are captioned (Space Mutiny, Time Chasers, Giant Spider Invasion), others are not (Manos, Future War, Laserblast). However, I’ve heard that some of these uncaptioned episodes do have captions elsewhere, such as Amazon Prime. My guess is that Amazon requires them for everything on the platform and some third-party service was engaged to caption them there.
So if all of them will be captioned for the Gizmoplex, that’s fantastic news. 