How do you say varsity soccer team in spanish?

The easiest answer would be:

"El equipo representativo de futbol".

In Mexico, futbol, in other Spanish-speaking countries fútbol.

However, "varsity" does not have a direct translation in Spanish. For instance,

futbol = soccer

equipo = team

represenativo = that represents.

Sometimes, "representativo" could qualify for a school, but sometimes it can be a subset within the school, like the engineering department (equipo represenativo de ingeniería) or the political science club (equipo representativo del club de ciencias políticas). Hence, you are better off including the school you are refering to, such as:

"El equipo representativo de futbol de la universidad del este de Washington" (Eastern Washington varsity soccer team)