User blog comment:Kaido King of the Beasts/Chapter 884: Sing or Swim/@comment-31429799-20171103140934/@comment-24769684-20171107194413

This chapter explicitly confirms that Katakuri doesn't merely transform his body into mochi like a Logia user would. He alters the shape of his body to dodge attacks and leave mochi in its place. Information regarding that is in both his article and the Mochi Mochi article.