- release 2 element jutsu at once* : mei, yamato, haku

- kakuzu can't "release 2 element at once", he need his "puppet", each puppet only have 1 element. kakashi have more than 2 element but can't release it all at once (but he had sharingan implant same as danzo: blood limit)

- kidomaru t's just experiment humanoid

- orochimaru, kisame is just characterism from kishimoto & still mystery (sage mode?)

IMO Kishimoto not calls Orochimaru is sage mode because Orochimaru's looks already like 'sage mode' since kid, so it will fail explanation. Also Kisame already looks like shark since kid, some sword-water ninja have taper tooth... so better became a mystery (no explaination).