Tekken Tag Tournament Tips

Play as Gold Tetsujin
Win 10 consecutive matches in "Versus battle" or "1 on 1 Versus" mode, then select Tetsujin. Tetsujin will remain gold until the win streak is broken, or Versus mode is exited.

Another way is to win 10 consecutive matches in "Survival Mode" with Tetsujin as one of the members of the tag team. Then for the rest of Survival mode, Tetsujin will be gold until you are defeated.