The P visa is a temporary employment visa given to internationally recognized entertainers, artists and athletes, as well as their spouses and/or children. The P visa typically applies to individual or team athletes or members of a large entertainment group, such as a band.
The P1 classification only applies to team or individual athletes or entertainers. Typically, the US issues about 25,000 of these visas annually. The P2 designation is only for entertainers that are performing under a reciprocal exchange program.
The P3 visa is only for artists who will be performing under a program designated as being culturally unique, and P4 visas are for the spouses and/or children under 21-years of age who are traveling with or about to join the P1 holder.
Given the nature of this visa, a complete sports team may file for a P1 to allow the team entrance into the US. They must be recognized internationally as a team, or if an individual applies, they must be considered famous, for example, David Beckham.
Other criteria that needs to be met includes that the event the athletes are participating in must have a good reputation and only require those of excellent caliber, skills and fame to be involved, for instance the Winter or Summer Olympics.