Its the opposite of Wolf. Wolf shares all of Fox's base B moves (that includes FS) with altered properties, but Wolf has his own completely different A moves.
Jigglypuff went the extreme opposite route (in Smash 64, I want to be clear). Completely different B moves, so many shared A moves with Kirby.
I copied this from ssbwiki
"Both share similar forward smashes, down smashes, neutral aerials, forward aerials (Kirby's hits multiple times, but he extends both legs in front of him as does Jigglypuff), down aerials, tilts, back throws, item animations, and ledge animations. Both also have near identical physics, with similar size, shape, weight, and falling speed, and both have five midair jumps (while all ten other characters have one). Their special moves, however, are all completely different. "
https://www.ssbwiki.com/Clone