Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Also, I have a couple of minor criticisms about the theme. The main one is that you should make the Mega Evolution button a lot smaller. You should also make the menusprites smaller. Other than that, nice theme!
Do you know where the line of code is for Dark Theme background images during battles? Since I'm going to change it like I usually do, it seems it's moved since previous updates and I can't locate it.