Board Thread:Theories and Speculation/@comment-24824859-20150704165201/@comment-6769189-20150717150008

Afterlife Kamui: chakra is mental/spiritual and physical energy, physical energy doesn't necessarily come from a body. As a spirit its possible that physical energy is gathered from around them. Like the theories behind why cold spots and emf spikes occur when a ghost tries to do something. Its also been shown that chakra can be independent from a physical body. Also, he had 6 Paths Power so he gets to do stuff that normally can't be done

Sharingan: the eyes are special. The initial activation comes from the brain, after that they physically changes. An uchiha may not ve able to activate the Sharingan if they hace a non-uchiha eye.

Susanoo: was never really tied to an the eyes. Mangekyou is probably necessaru to unlock it, but not necessary to activate it after.