Short & Sweet Story
Raditz has come to Asgard and wishes to fight Thor. Simple Story. Nuff Said.(Why or how he would know about Asgard is unknown =p)
No Prep(Like it would Matter)
Battle takes place in Asgard on the Rainbow Bridge.
If this is spite on Thor then he can get his fellow Avengers:Captain America & Iron Man(Mark VII) to assist
If this is spite on Raditz, then he gets a Saibemen(Same exact powerlevel as Raditz, but much lower power output)
P.S.- That pic of Thor is soo bad@$$