Sponsoring will take a lot of money and a lot of hassle.
The process is quite tedious. The person you want to sponsor will have to be established as an 'acclaimed' athlete, which means they will need to have national titles & international achievements. They will need to be published in publications. You will need advisory opinions from established dance governing bodies as well as renowned coaches with world titles.
Just to give you an idea, attorney fees alone will be $3500-$5000. Then you have to pay the actual filing processing fee (not too bad, I think $200). This could take months, and you have the option to pay an additional $1000 to expedite which will be processed within 15 days.
All of the above will only give the dancer a 'petition approval', IF it is granted. Then the dancer still has to get an appointment in his/her own country to interview with the US Consulate. Typically they will not deny the visa after the 'petition approval' is obtained. But there's no guarantee.
Of course, to get an interview overseas, there's additional fee.
So my advice would be unless you plan to be the top US dancer, and really need a world class competitor as your partner, you are better off doing more search in the US. Pro/Am is another option to market yourself to land a partner. And at the end may be less complicated and less costly (believe it or not!)
The sponsored athlete technically can work legally in the US. However, NDCA will not permit that for amateur unless you're top in the Nationals - which was just held this past weekend.
So that means you will have to pay his/her living expenses and the airfare to come to the US. Also perhaps medical insurance. These foreigners also tend to be very tight financially, so you will have to pay for the private lessons to train and all the travelling expenses to compete.
Think many times over before you decide to attempt this...
