Roberson transferred after two years with UConn.
Parsons played for the Nittany Lions in 2018 and 2019.
Fashanu will play for four years, earning $20,510,710 with a fifth-year option.
McClain's stop with the Sun Devils will be the third of his college career.
Mack reportedly entered the portal on Thursday, May 2.
Robinson played for the Nittany Lions from 2011-13, recording 177 receptions for 2,474 yards and 17 touchdowns.