Board Thread:Questions and Answers/@comment-46731117-20200826115351/@comment-29325824-20200826115854

Considering Shinigami are merely regular Souls with high spiritual power who's powers come from being given an (artificially created) Asauchi, I think that, in theory, any spiritual beings should be able to imprint upon an Asauchi. From Fullbringers, to Quincy, to Arrancar.

The only reason that likely never happens is because the existing Asauchi are under strict control of the Gotei 13, and Nimaiya is the only one who knows how to make them anyway.