No certain time. For the most part I just do random battles on GBU. A Brave, 0 speed D-
Punch Metagross is the missing link in my team. (Triples Gravity team)
I'd prefer it sent in Gen 4, so I can clone and get 4th Gen tutors, but it's not completely necessary. I may, or may not want one with Gravity.
If you'd be willing to go a little further, I'd be in the market for Careful, flawless (+SpDef/-SpAtk) and Sassy, 0 Speed (+SpDef/-Speed) ones too.