Quote Originally Posted by Sam
Before Japanese had their Headmasters portion ... was the G1 cartoon exactly the same as the US version?
Pretty much, yes. There are a few minor discrepancies, such as RIRFIB (whereas the US cartoon is notoriously FIRRIB) and season 3 occurs in 2005/6 whereas in Japanese continuity it occurs in 2010. Oh yeah, Scramble City. But otherwise it's the same.

Quote Originally Posted by Sam
Main reason I am asking is because I am curious about how the Autobots (of the Japanese version) got their "Athenia" base. Hope I'm making sense.... thanks!
The planet Athenia was first seen in "Five Faces of Darkness Part 1." It was a really weird non-spherical planetoid (like the planet of Junk, only not made of garbage) and was the place where the first Galactic Olympics were held. By the time of "The Headmasters" (2011) Athenia had become heavily terraformed into a completely spherical planet and colonised by Autobots.