i dnt feel as though jiraya can beat oro, sage mode or not because has 2 immortality transformations....the Great White Serpent, and the 8 Headed Hydra both are immortal and can only be beaten by being sealed so oro beats sm jiraya
and most physical damage wont work on oro
oro > jiraya which would make him not even able to go into sage mode but i will give it too him...
sage mode or not he cant beat the 2 immortal transformations
also as for their students its hard to say because naruto, i can match them up
ems sasuke vs bsm naruto-which i can make a case for reason why both win
dsm kabuto vs nagato-without edo tensei nagato wins low-mid diff but with edo tensei he loses mid diff( excluding edo madara and edo itachi because they can break free of control any time they want)...
suigetsu/sakon/udon vs konan- im almost sure suigetsu wins because of his clans kg which water > paper, although she did overcome that weakness by putting oil on her paper but that still means she cannot grab suigetsu or touch him at all, and sakon and udon's kg is beast
kimimaru/jirobo/tayuya/karin/kidomaru vs minato-i think they could counter ftg but one of them will probably die just to obtain intel on it, but kimimaru can take the rasegan's due to his kg and jirobo is a above average doton user, and he can easily create the dome as minato throws the ftg tagged kunai, while kidomaru sets a well calculated strategy with his webs that minato wont be able to break and tayuya uses her sound genjutsu to subdue him...remember he cant stay in s/t so he will be caught in that jutsu unless he targets her first...