FreeGameDev

Are possible create 3 strike battle-mode for single player only (with auto-control opponent)
and option for select kart that is to be opponent (not about how many number and random only)one by one ?

no, that is not possible yet. it will be in the near future, but not for a while. If you want, you can turn on artist-debug-mode and then you can play with only one kart.....but that is really for testing arenas and not really playing them.....
hope this helped,
ctdabomb

"Near future" may be a bit strong. As far as I'm aware there's no AI for this at the moment.