80's all-star vs. 90's all-star vs. 2k's all-star vs. up-and-coming stars? who will win?

It so difficult comparing players across decades, but since you forced the issue, I'd go with the 80s, the Golden Era of the NBA. The arguably 6 or 7 of the top 20 of ALL TIME played in that era. Guys like Jordan, Barkley, Hakeem, and Stockton could move between the 80s and 90s since their careers were divided between the two decades. Plus, you still have Magic and Bird, and some of the older stars from the 70s in Dr. J and Kareem. Amazing decade.