They’re all pretty versatile. Zubin started out as a drummer before turning bassist. Joe composes much of his compositions on keyboards as well as guitar. I’ve never known Rob (guitar), Andrew (piano) or Ross (drums) to play other instruments but that doesn’t mean they can’t.
For a list of specific kinds of instruments they play, check out the Tally Hallmanac: http://www.hiddeninthesand.com/wiki/index.php?title=Tally_Hall#Equipment_List