Here’s a cut scene from Dragon Ball Z Budokai Tenkaichi 3 which features the mega powerful Super Saiyan 3 Broly. In the game he seems to be the most powerful character by far and it will be interesting to see how DBZ games evolve now we have Birusu and others who in an alternate reality would potentially be more powerful.
http://www.youtube.com/watch?v=r_Qb2sxXSjw