Greymon could do very little against any of the brothers but just tank their attacks, but just the fact that he was able to tank repeated attacks from 2 of them at once (Mamemon and BigMamemon I believe) doesn't speak well for those ones beating Etemon. I mean yes, Greymon is definitely a lot stronger in 02 but is he really THAT much stronger?
Giromon and MetalMamemon were individually matched or even overwhelmed by an Angemon that wasn't trying to kill them and it took both of them at once to actually overwhelm him (yet this is somehow the scene that PROVES Angemon is no stronger than a regular Adult sans type BS lol) but even being able to do that at all (2v1 or not) is well beyond the likes of Base Etemon.
I could see Etemon taking down Mamemon and BigMamemon but losing soundly to MetalMamemon and Giromon.
I think it basically goes the same as the first scenario. Angemon (with or without the type advantage) is absolutely stronger than 01 MetalGreymon who would be superior to either of those guys especially by the end of that season.
Meaning Mamemon and BigMamemon aren't much use but Giromon and MetalMamemon should take them down.