Alive Minato can't use BM. I assume with alive BM Minato you meant an Edo Tensei version of him minus regeneration.
Edo BM Minato wins. He has multiple options to get past Perfect Susano'o. Perfect Susano'o sword slashes are tanked by Minato's avatar considering Naruto with his avatar which is Kurama's other half defended against Jūbi's beam using 6 of its tails. Jūbi's beam power output was so immense it vaporised several mountain ranges at a time.
Since Minato can teleport away everything that comes in direct contact with his body or chakra, Hiraishin can be used to remove Perfect Susano'o from Madara by touching it with Kurama's avatar tails. With his defence gone tail swipes destroy Madara's body or a clone decapitates him. Alternatively Minato can mark Perfect Susano'o with Hiraishin and teleport Renzoku Bijūdama or Flash Bijūdama directly on it bursting it apart.