In case anyone is interested, "Battle of the Planets" (this version specifically; i.e., the initial Sandy Frank "dub"* from 1979 [I think]) is now available on Hulu.
"Battle of the Planets", indeed. TBH, I actually didn't expect this version to appear anywhere, let alone on Hulu. I wonder if this means we can expect Sandy Frank's later "G-Force: Guardians of Space" dub (which is [somewhat] truer to the original version)...
*If one can really call it that. Originally, there was no "7-Zark-7" robot. I think this was one of the earliest instances of a "Macekre" (Tetsujin 28-gou/Gigantor was first though; originally it was set in the 1940s just after WWII, but the dub changed the setting to "the year 2000"). G-Force (as they were also called in this version) supposedly traveled to other planets based on various Earth locations. The original "Gatchaman" team (and by extension, the later "G-Force" team) did no such thing.