Complex sentence: Sweetnam began working on new music in 2009 and formed a new band, Sumo Cyco, a four-piece heavy metal and punk rock band that opened for Hollywood Undead in Toronto in April 2011.
Split into simpler sentences: Sweetnam began working on new music in 2009, also forming a new band, Sumo Cyco. They are a four-piece metal band who opened for Hollywood Undead in Toronto in April 2011.