-1
The biggest issue here would be that players would just flood to the server with better exclusives and effectively just lead the other as "dex only". Lets say spawns work like they did in Black 2 and White 2 where one got Gible and the other Solosis, then players would just flood to get Gible. On paper it looks like an interesting change, but it would hinder some on PvP even due to some possibly being able to transfer more quickly and frequently than some. Flooding the better exclusives server would also probably not go well for server stability, and at that rate if players just choose one over the other then we may as well just have a single server. If spawn exclusives are just the less captured pokemon like Shelmet - Karrablast or Growlithe - Vulpix then the change also wont impact anything other than just adding another step to getting a full dex that players are forced to pay into other players or do themselves with a transfer option only allowed with coins or once a month. Plus, if a server ever crashes or remains unstable for an extended amount of time then pokemon exclusive to said server become practically unobtainable until the issue is resolved. Having the time change would work alright, and even having some legendary options would also work since those would be more as a preference or one time deal. I just think having different spawns amongst both would not go over well, since it just encourages players to go to the "better" server based solely on what can be found.