It only depends of one thing: The power lvl of Darkseid.
Usually, Darkseid is portrayed as someone with enormous power, but with strenght on Superman lvl. With this version, Thanos would almost soloes.
If we use a Darkseid more powerful than that, a version that can compete with Thanos, Team A would win, because the helpers of DS are so better than Thanos' it's not even funny. Only BRB is a real challenge to them. And Surfer and Thor destroy him, and Marvel would hold his own.