There's no single general definition of what counts as a Gundam

Gundams are whatever it represents, significantly, in that universe. As long as there's something that makes it a Gundam, something unique, or special, then that makes it a Gundam.

Mobile suits built from Gundanium alloys (Wing).A product of the G project, the G.U.N.D.A.M. (Seed). The mobile suits equipped with the true GN Drives (00). The 72 Anti-Mobile Armor Gundam Frames (IBO). The controversial mobile suits equipped with the forbidden GUND format (WFM).

Now the Rogue Orbit is a completely different timeline so what makes it a Gundam or how it counts as a Gundam depends on what a Gundam in that universe means.

"Nooo, that doesn't look like a Gundam.," "No, that's not a Gundam." BY WHAT STANDARDS??

GUNDAMS ARE WHATEVER THAT UNIVERSE'S GUNDAMS ARE.