I'm interested in a quite a few.
What if Venusaur, Blastoise, Alakazam, Gengar, Kangaskhan, Pinsir, Gyarados, Aerodactyl, Ampharos, Scizor, Heracross, Houndoom, Tyranitar, Blaziken, Gardevoir, Mawile, Aggron, Medicham, Manectric, Banette, Absol, Garchomp, Lucario, Abomasnow, Beedrill, Pidgeot, Slowbro, Steelix, Sceptile, Swampert, Sableye, Sharpedo, Camerupt, Altaria, Glalie, Salamence, Metagross, Latias, Latios, Rayquaze, Lopunny, Gallade, Audino, and Diancie all got mega evolutions? How awesome would that be?
What if they even one-upped that and gave certain pokemon like Charizard and Mewtwo...not one, but TWO mega evolutions?