This is actually a very interesting match up... I believe it would be incredibly difficult for either of them to be victories.
The both have knowledge on each other abilities as they were training and fighting with one another since they were little. This is why it's extremely tricky.
Jiraiya is know from his incredible offensive skills and has shown a vast amount of Jutsu, in fire and earth type jutsu which he uses exstremely well. Jiraiya is also very smart and has great physical strength, however it's nothing compared to Tsunade, so close range combat is useless against someone who is a close combat range fighter.
However, Jiraiya has also shown that he can attack from long range distances with his hair that shoots vast amounts of needles and also works as a defense.
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Jiraiya is also at an advantage in this fight due to his incredible summons. which include Gamabunta, Gamaken, Gamahiro, Gamakichi and Gamatatsu. Let's not forget his biggest asses which is Maa & Paa
Jiraiya can also use collaboration jutsu as his long range attacks, which uses less chakra however... it multiplies the strength of the attack.
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These toads are not only a major thread for Tsunade however, they also have a wide range of knowledge that can act at there own accord, which mean's jiraiya does not waste any chakra having to control them.
These toads are incredibly big and strong, who have great reflex's and can jump extremely high which gives them an advantage when they attack from the Sky.
Jiraiya also has the ability to enter sage mode with Maa & Paa. Which can increase his Strength, senses, chakra and speed. Maa & Paa also have the ability to have cast an incredible Genjutsu....
This could be a massive advantage against tsunade, as she's a close range fighter.
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Tsunade on the other hand is no push over as she a Senju who are known for their incredible chakra reserves. She's also known for her incredible strength which is do dangerous that one punch from her and it's Game Over!!
Tsunade's physical strength is her massive advantage as she's able to shack the ground and create massive creators which just one punch. Jiraiya himself even stated, that in his life he has only been in two near death experience, one was when tsunade caught him peeking he punched him so hard that he broke several bones.
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Jiraiya can not take tsunade in taijutsu as he would be ricking so much, his only change would to be use long range attacks, which is harder said than done because tsunade isn't exactly slow.
Tsunade's is not only known for her incredible strength but known for her incredible and genius abilities as a medical ninja, which are a massive asset in repairs fetal wounds.
Tsunade also has the ability to rapidly repair cells and organs making her invisible for a limited amount of time....
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Even swords going right through her have no effect...
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Tsunade also have incredible will power which she has shown on many occasions....
Both having knowledge this fight could go either way...
..... is this serious? Tsunade isn't that strong at all, jiraiya should be the hokage but he didn't want to, a better question is who is stronger: Jiraiya or Orochimaru? then I would say in shippuden jiraya but in naruto orochimaru, but if tsunade will strip then it's bye bye jiraiya
jiraiya has sound genjutsu which tsunade will just fall threw since her animal summons and her will get caught and jiraiya would be faster than her in sage mode and can use that to his advantage.