Itachi said the best he could do against Jiraiya was match him. With Oro, that would make it extremely difficult. If Kisame used Samehada against Jman (especially if he was fused with it), it would be rendered useless because of the effects that come with absorbing nature chakra. No one has an elemental advantage because Itachi's Fire trumps Oro's Wind, but Jman's Earth trumps Kisame's Water. Oro and Jman have the advantage on summoning because they have huge animals to summon, while Itachi summons crows and Kisame summons sharks. I don't believe that Itachi can put Jiraiya under a genjutsu due to him being fused with Ma and Pa. For these reasons, I think Oro and Jman would beat Kisame and Itachi.