Complex sentence: He worked for the school's parent federation of Slammers Wrestling Federation for a time, losing his first professional match there to El Sprito, working under the name Iron Mike Erhardt.
Split into simpler sentences: He worked for the school's parent company the Slammers Wrestling Federation for a time, losing his first professional match there to El Sprito. In the Slammers Wrestling Federation, he worked under the name Iron Mike Erhardt.