Speculations "Rubber shouldn't be able to do this!!"

His awakening will be different from rubber but close from stretching or devil fruit have two powers one obvious and other hidden you can't reaching it only buy awakening, and G4 was just a hint from this awakening
It feels more like Katakuri who was able to change shape despite not being a logia.

The Gomu Gomu no Mi might be a Special Paramecia as well. With how much alike Luffy's and Katakuri's powers were depicted, I wouldn't be surprised.

And besides, King and Sasaki did weird things in their fights that they shouldn't be able to do based on their fruits, so Kaido's statement doesn't seem THAT important to me.