Chopper can manipulate dfs more specifically Zoan devil fruits.
And he can make transforming to things not possible both voluntary and permanent
he is privy to knowledge that Only three people have clearance to so far... but we will get to that later
He can create more possible transformations
Meaning he understands how DF's in essence work and can manipulate them to do more. Since he understands how complete zoans affect the body using his knowledge of medicine he could know what is missing or off about Momo's failed fruit. If only temporary through the rumble ball he could make momo change into more complete versions of his dragon form. And using what he learned post time skip he can make these changes permanent.
He is privy to knowledge that scientist the caliber of Vegapunk knew because he has gotten his hands On C.A.N.D.Y. Which dr kurena knew of and at fish man island said its insanely hard to get your hands on. So he knew the things Dr Keruna knew (Who had clearance to have the stuff Vegapunk knew).
If we put this together. He knows how Zoans work. He knows Vegapunks work and stuff only top caliber doctors and scientists know. (3 total people so far have been named with this clearance.) He can permanently manipulate the way zoans transform.
This right there makes me think that Chopper is the only person who can fix momo's devil fruit.
And he can make transforming to things not possible both voluntary and permanent
he is privy to knowledge that Only three people have clearance to so far... but we will get to that later
He can create more possible transformations
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If we put this together. He knows how Zoans work. He knows Vegapunks work and stuff only top caliber doctors and scientists know. (3 total people so far have been named with this clearance.) He can permanently manipulate the way zoans transform.
This right there makes me think that Chopper is the only person who can fix momo's devil fruit.