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.
It's probably too late to change anyone's opinion on this, but I may as well voice my thoughts. Mega Metagross has always seemed to echo shades of Greninja for me - it does not have the ridiculous amount of super effective coverage that the ninja frog did, but it makes up for it with a much...
I also frequently receive the JSON error when playing rated OU battles. It has made the app unusable, as I can do nothing except let the battle time out (and lose) when it happens. I don't know if the app has been updated or not since then, but I cannot install the newest APK. It just says...
My opponent and I are going to try to battle today, but due to time zone differences and the fact that I have been doing 10 hour days at work, we have not been able to get it done yet.