There's a Weekend Discussion Thread going on over at Satellite News right now about obscure TV shows that would make good riffing material, and I'll mention one thing here that I mentioned over there: the 1980's Johnny Sokko and his Flying Robot compilation movie Voyage into Space.
The original series was, of course, a 1967 Japanese teleseries in the same vein as similarly dubbed Japanese superhero shows from the mid 60’s that also became hits in America, such as Ultraman and The Space Giants. Like so many other Japanese tokusatsu (special effects) productions being made at that time (MST3K favorites Mighty Jack and Gamera vs Gyaos came out that same year), Johnny Sokko is filled with delightful goofiness, and the dub would make it an easy MST3K target. The Unicorn Chief, in particular, is given dialogue filled with “more gaps than a Pinter play”. The wild alien villains would also surely inspire some great material, especially the peg legged, striped shirted, buck toothed guy who looks like he walked out of an offensive WWII propaganda poster.
Anyway, in the 1980’s, a handful of episodes (including the pilot) were edited together, Master Ninja/Rocky Jones/Riding with Death style, into a TV movie called Voyage into Space. And, even though the movie wasn’t included, guess who put out the Johnny Sokko Complete Series DVD set a few years ago…
Shout! Factory.
As much as I love the show, it'd be fun seeing on MST3K, and it would certainly give them a lot to work with!