Devil_Hex
I think Fujin should try to improve his Water-Release by learning these Jutsus: Exploding Water Wave (B-Rank), Water Dragon Bullet (B-Rank), Water-Bullet (C-Rank), Wild Water Wave (C-Rank), Water Gunshot (C-Rank), Water-Clone (C-Rank), Water Prison (C-Rank), Hiding in Mist (D-Rank) & Water Needle (D-Rank).
the only other character he will fight is the one who uses lightning release, which the only jutsu he would need is the raikage armor, which however is difficult to reproduce with what is not even his main element. furthermore he will tend to use them little and the time spent learning and stealing these jutsu would be more useful for improving his main identity at this point, then training the wind release. also as he said in the dialogue with hiruzen, it doesn't make sense for him to waste too much time on elements other than his specialty (and lightning obviously). he has 4 years to fight madara, and I think this is his main goal, much more than developing secondary identities that only serve him on certain occasions
S_K_0017:Vertical growth for Fuijin's character cannot support the different personas he has created to operate Phantom-Heaven Society. Now, it's quite common knowledge that Fujin is Master/Grandmaster in these fields: Wind, Fire, Earth, Genjutsu & Fuinjutsu with some good knowledge of Medical Ninjutsu. For his other personas to succeed & avoid any connection with him, he needs an entirely different skillset based: Lightning & Water as these are complementary Nature-releases. His different personas can disguise themselves as rogue Shinobi from Iwakagure, Kumogakure or Kirigakure. I hope that Fujin's medical knowledge will improve to such an extent that he can study "Hiruko's body & Chimera Technique" & use it combine his Wind & Lightning release to create: Swift Release Kekkei-Genkai. Fujin should be able to use "Griffon Senjutsu" to achieve the stability required to merge the above Chakra Natures under Chimera Technique. Fujin should create a "Swift Release Chakra Armour" Jutsu based on Lightning-Armour that should allow him to match Naruto's physical speed in the KCM-2 mode.