Hey I have been hunting Thundurus all day (doing premier ball challenge too!) And as many times as I caught it no luck on brave yet! I will be trying again today so bear with me! As for the battle, sure! I will be using Pokemon X though
Unfortunately, the only 5th gen game I have is SS. I could only do it in 5th gen myself, otherwise I would have to look around to see if anyone that has D/P/Pt could get the Regigigas.
Blast, that will be hard as I am not entirely sure as to how to get a Regigigas on my own so I could Nickname it. It would be easier in 5th gen for me.