Complex sentence: At WrestleMania XX, Guerrero retained the WWE Championship against Angle, before losing the title to John "Bradshaw" Layfield in June, when Angle, then-SmackDown !
Split into simpler sentences: At WrestleMania XX, Guerrero retained the WWE Championship against Angle. Guerrero lost the title to John "Bradshaw" Layfield in June, when Angle, then-SmackDown!