Tsunade wins mid difficulty. Decapitating someone isn't all that easy especially when Kakashi with the sharingan has had trouble killing his opponents via Raikiri blitz let alone decapitating someone without the sharingan.
Tsunade isn't getting paralysed with mere raiton because she can control the nervous system's electrical synopsis and Sasuke managed to resist paralysis due to his raiton affinity. Tsunade isn't a raiton specialist but her being able to convert her chakra into electricity for the purposes of accurately disrupting the nervous system means she has the medical expertise in resisting paralysis. Kakashi's suiton is tanked with ease and the knockback from suiton is useless when Tsunade can put chakra in her feat.
Kakashi's clones get destroyed by a punch/kick to the ground.
If Katsuyu is summoned, Kakashi is screwed because even though raiton is dangerous for the slug, it can split many times so Kakashi can't take them all out. Furthermore, Tsunade can just intercept any raiton that Kakashi decides to throw at Katsuyu or she can simply heal Katsuyu since the two of them have a link which allows Tsunade to transfer her medical ninjutsu to Katsuyu.