KIsame can't handle a TBB. The most likely scenario was that Roshi didn't get to go full Biju mode against Kisme just like Bee. Remember, the biggest obstacle Kisame faced against him was his Yoton—meaning he never got to face a TBB. Also, his chakra-sucking abilities make him a bad opponent for Jinchuriki. You can't use that to say he's better than others in a fight. And this is a teenage Minato who needs to use hand signs for FTG facing two Jinchuriki. So there isn't much J-man could do here. If this is prime Minato, he'd have sent the TBBs back at them lmao.
Nah, Aizen was always stronger than Isshin, but this is a bit different. Madara was on the same general level as Izuna and Tobirama before EMS. Even if we're to restrict prime Madara to MS, he wouldn't beat Minato. Among those beneath Hashirama, he's clear of anyone not named Madara, or Nagato, and it's debatable with Itachi and Shisui due to genjutsu. Itachi and Shisui probably scale up to MS Madara if not better, and they only pose a threat to Minato thanks to their genjutsu prowess, at which they're both better than Madara.
Susano's no threat to Minato. Bro's reactions are beyond even EMS Madara, forget MS.