thanks ugly god
mega-aggron is the only reason rock is viable as a monotype, and to remove aggronite is to condemn rock to the worst of all types
mega-gyarados isn't even the mega of choice for flying teams (usually charizard), but it's not like it gains an awesome new attacking STAB, and along with megazard Y it is flying's best method of dealing with rotom-W
mega-zard X still looks like a flying mon, and flying teams will appreciate something that isn't weak to bolt-beam (unheard of for flying thus far). If anything I would insist zardX be allowed on dragon, as dragon teams really need something neutral to fairy (sorry dragalge) and immune to burns
My proposition is to allow select megas (zard-x, amphy, gyara, pinsir, and later on sceptile/audino/altaria, etc). to be playable starting in mega form, so that they can be used on teams that share typing only after mega-evolution
Flying has many ways to deal with rotom-wash, including Zapdos, Charizard-X, Charizard-Y, Dragonite, Articuno, etc..
Also to your proposition to allow megas to start in their mega form, that would go against game mechanics and the way mega evolutions were intended to work. For example, charizard x would not take the extra stealth rock damage.
this isnt hackmons :^(