I'm so excited for the 6th generation as I get to verify an old theory of mine:
Every pokemon with 495(the pokemon with the highest BST to evolve and gain BST is Magmar) or less that doesn't have three evolutions is eligible for an evolution. Others with higher BSTs(>495) could get a pre-evo and the ones that have 500 BST could get an evolution but with no stat gain(scyther ->scizor)(only a redistribution of their stats). The only pokemon that is an exception to this rule is porygon which can be considered an artificial/man made pokemon to which this rule does not apply.
If this pattern holds true then it means that pokemon like: Accelgor(495), Escavalier(495), Floatzel(495), Mismagius(495), Abomasnow(494) and everyhting with lower BSTs ,that doesn't have three stages and isn't a fossil COULD ,in theory, gain an evolution(not necessarily in this gen).
Sadly this also means that pokemon like: Zembstrika(497), Drifblim(498) and the Simis(sage,pour and sear)(498) would be just outside the evolution range. Of course everything bellow 500 BST could evolve but to date the highest BST pokemon to ever evolve with BST increase was Magmar(495).
Pokemon like Wailord, Ursaring, Rapidash, Pinsir, Muk, Heracross, Houndoom, Golduck, Drapion, Donphan, Claydoll and Bronzong who all have 500 BST could gain an evolution but with same BST(only stat redistribution). Everything above 500 would not get an evolution. As of yet in 5 generation this pattern holds true.
Of course I could be wrong in which case everything goes. :)
Also I like the IV system as it is. Every pokemon should be unique. What I'm about to say next will surely not make me many friends. IT IS SUPPOSED TO BE HARD TO GET THE PERFECT POKEMON else everyone and their mother would have the same one. Only those that have the patience to breed the pokemon should be able to have them. It takes a lot of hard work to get a pokemon with perfect IVs, best ability and best nature. If you don't put in the work then why should you have such a pokemon? You could ask a breeder friend of yours if hes willing to trade you one if you really want one. This however will cost you. Its not like you can't play on the simulator with pokemon with perfect IVs. For official tournaments though why should you have the same IVs on your pokemon as someone that painstakingly went through all the trouble and bred himself these pokemon. It just doesn't seem fair to me. I'm sorry, but this is how i see it. If you're a truly good trainer you should be able to beat your adversary even with this handicap. If you're not willing to put in the time to breed you're own then you don't want to win badly enough. This is not directed at anyone in particular , I'm just speaking my mind.
I would very much want every species of pokemon to have a height range and each individual should have a random height from that range. The height should be visible if you put two pokemon of the same species on the field at the same time.