Obito's sharingan & spirit bonded with Kakashi because his MS awakened in Kakashi's eye socket, remember?
Obito also unlocked his sharingan starting at 2tomoe & skipping 1tomoe , his sharingan has never used 1tomoe, remember?
Obito (hagoromo) former juubi-jin. Obito (ashura/indra) transmigrated his "spirit/chakra" into kakashi.
Obito (hagoromo) gave kakashi(Naruto/sasuke) a power-up , the sharingan & "Perfect Susano'o".
Dan used his ghost jutsu to replenish Tsunade's chakra & Tobirama suggested doing the same for Sasuke.
Obito's sharingan/powers skip steps normal Uchiha have to go through. Obito also combined with Senju dna.
Madara/Sasuke(both indra transmigrations) had to go through each stage of sharingan, but Obito didn't .
Obito's different than others, much different.