Mega Evolution Bug

[BugReporterSneaky]

While in battle after you mega evolve a pokémon you are´nt able to mega evolve others after the first one. e.g.: When battling Harmony I mega evolved my Typlhosion and after he died i switched into my Delta Charizard and the sprite (icon of mega evolution with the z key) was missing. I pressed z regardless and attacked and he didn´t evolve.

[Sam Carlberg]

You should only be able to mega evolve one pokemon per battle so that sounds like it's working as it should

http://bulbapedia.bulbagarden.net/wiki/Mega_Evolution#In_battle