Jiriaya never "truly" tried to beat oro. Why? It was a feelings relationship. See what's going on with Sasuke/sakura/Naruto that is the same with the 3 sannins only with Tsunade I don't think ever loved Oro, but she showed feelings when Jiriaya went to fight Pain and died. I think she loved him. And i hate when people bring up the 3 sannin fight all 3 were handicap or impaired. But then you can argue it was 2v2 not counting summons, but why wouldn't you want to see the sannin fight each other.
And Oro was scared of Itachi....why he leave akatsuki? Because of Itachi, so Itachi > Oro. And there would be no purpose in training sasuke...
Kisame vs Oro is a toss up. It can be argued either way. One side has Sameheada and huge chakra reserves while the other one has forbidden justus, kusangi,and you can say I guess a huge chakra reserves also.