Oh god, please no SymphoGear... x_x

Meta-gaming and God-moding will always be a problem, no matter what you use as a counter-measure (aside from outright killing your players if they do any of it). Some people just can't (or don't want to) play fair, and others do it either subconsciously or without thinking too much. 

However, certain ideas simply don't work, one of them is countering over-poweredness with more over-poweredness. Since, eventually, you'll end up with [i]The Unstoppable Force[/i] clashing against [i]The Unmovable Object[/i], and then you just end up with the galaxy imploding and everyone text-messaging you a bunch of frowny-face emoticons.

Not telling people what you've prepared doesn't work either, since then you can just pull shit outta your ass - litteraly. "Oh, you're attacking me with your beam-sword? Well too bad! I prepared a mirror trap that reflects all beam attacks! Oh? You dodged it? Well done, too bad I had pit-falls dug where you dodged to!" and so on and on it goes, with both sides having "secretly" prepared "hidden counter-measures" for all eternity.

In the end though, does it really matter? If SKys is goiung to use Eye Space, or something similar, for the battles, then there won't be any need for traps or tricks, since - quite simply - you won't have time to set those up. The best thing you could do would be something like, attacking a single person with allies or other magicians and ganging up on one guy, or distract said guy while you let someone else blast him/her from afar. This won't be Fate/ with things like Bounded Fields and Reality Marbles after all.

At least, there has been no mention of bounded Fields or Reality Marbles thus far...