I don't even know if this is an actuality since I really don't feel like registering for yet another forum, but I think that doing three metagames for each generation is a bad idea.
Put quite simply, the RBY and GSC uber metagames are too undeveloped to play competitively. I don't know much about the power of Mewtwo and Mew in RBY (besides the Amnesia Mewtwo thing), but the GSC uber metagame is, in my experiments with it, geared to be even more stall-orientated than the standard metagame. You could do standard and underused, but RS is the only generation with enough uber checks and balances to consider an uber metagame--in my opinion, even doing only an RS metagame is unfair to GSC and RBY, as it puts more emphasis on RS wins than on RBY and GSC. After all, we're supposed to be the authority on ALL aspects of internet pokemon, not just the most recent generation.