There is only
Purple coloured Genesect
Red coloured shiny Genesect.
However, in SSBM (super smash bros madness), there is also
-A grey coloured white-eyed Genesect
-A green coloured purple-eyed Genesect
-A golden coloured blue-eyed Genesect
-A black coloured red-eyed Genesect
That might be what you are thinking of, or maybe you saw fan-art or are thinking of green because it is part bug-type.