The GTS have an error that they still haven't restricted. People ask for legendary Pokemon under Level 10, which is merely impossible.
The only legendary Pokemon that can be obtained at such a low level is Regigigas in Platinum where you need the Regi trio, and a choice of Dialga, Palkia and Giratina in HGSS. You need the 12th movie Arceus though.
Since Zekrom is not on this list, there is no way you can get Zekrom under Level 9. The only way you can do it is through hacking via GameShark codes, or those cheaty Pokemon sites on the internet that create hacked Pokemon for you.
It is incredibly annoying when people in the GTS ask this, I know. Don't be tempted to hack to get the Pokemon though - it might ruin your game.
Sorry about that.
Hope I helped. :)