Hello again, Kimconu,
"Bigbang" is unlike any team name I've heard of. I don't watch or follow sports and never have, but all the team names with which I'm familiar -- at the professional, college, and high school level -- begin with "the": the Lakers, the 49ers, the Chargers (the name of my high school's teams), the Gauchos (the name of the U.C. Santa Barbara team), the Banana Slugs (the name of my alma mater's teams), the Dodgers, the A's, the Reds, the Seahawks, the Ducks, etc.
So let me adapt your team name to what I'm familiar with. Instead of speaking of "Bigbang," lets speak of "the Bigbangers." Members of the team could say, "I am a Bigbanger," "We are the Bigbangers." Others could refer to them by saying, "He is a Bigbanger," "They are the Bigbangers," etc. If one were looking at a photograph, one might point to a group of people in the photograph and say, "These (people) are the Bigbangers."