CHUG = Classics, Henkei, Universe/United, Generations.

It's the term used by fans to describe the ongoing toyline that started in 2006 with Classics as it's had a ton of name changes over the years. War For Cybertron Siege is the most recent.

CHUG Metroplex refers to four different Metroplexs that were released in the 2013. The Generations release, The Takara Genenerations release, the SDCC release and the AKG-Con release. All use the same mould with minor deco changes between them.

https://tfwiki.net/wiki/Metroplex_(G1)#Generations