Just kinda coming in here. Hello. I'd like to joint this project as well, it seems VERY interesting. As a matter of fact, I think I might be of some service in one way or another. (Probably won't be able to update as frequently on my end though. I'm pretty busy lately.)
Anyhow, even though I quite literally just got here, I'd like to give my opinion on a few of this issues currently at hand. (Based on KillerCroCohen's post):
a.Mega Pidgeot should stay Normal/Flying, as it was the one to first have this typing.
b.With Mega Fearow I liked the idea of Flying/Fighting, but also make it in such a way that it's not just another Hawlucha.
c.Mega Arbok's ability... not quite sure what to think of the ideas, they both kinda got juggled to the point where I'm not sure which is which. However, what I THINK is the Venom Fangs idea sounds good.
d. With Mega Raichu, I quite wish the rule of only one mega hadn't already been placed. The entire Pikachu family is mixed attacking, so I would think it would be better to either have a mixed attacking Mega, or two megas that prioritize. However, neither of those seem to be possible at this point. However, if I were to choose one over the other, I'd go for the special attacker.
e. On Mega Sandslash, I like the original Sand Claws idea, the one classic made seems interesting, but the original sounds nicer for Mega Sandslash. As far as stats go, it's a fine spread.