You're using ABC logic bro, that doesn't work. The sad thing is, and this is a major flaw in Jiraiyas' ability is that it takes time to go into SM.
Minato: They both have contracts with toads, so that automatically rules out toads. I'll give J man Ma and Pa though. It takes time for him to get into sage mode, and Jiraiya has to keep his hands together. Minato can finish him off in a matter of seconds then.
Itachi: Automatic Tsukuyomi. In reality, it's only one second. That isn't enough time for Ma and Pa to break him out of it.
Kabuto: Itachi never soloed him. He had Sasuke with him. White rage kills.
Jiraiya v Minato would be a lot closer than you're suggesting
it could go either way imo, Jiraiya is a tough sob and minato is quick as hell
so who really knows who would win that one
and Itachi never just uses genjutsu at the beginning (close to it v kabuto) so it wouldn't go down like that
Jiraiya knowing not to look in his eyes would make the fight an actual fight
Itachi feared fighting Jiraiya not cause he thought he would lose but because he thought he could die or be severely injured
they never really fought so it could go either way as well, with a slight edge to itachi
and Itachi did solo Kabuto, Sasuke didn't do anything he just stood there and yelled a few times