When complete, does the creature get the skill it had or its statuses back?
What happens if one of the pieces is targeted by Fractal, TU, or Mitosis?
Good questions. When the core reverts it become the original creature, so skills should come back. Also, you made me think about status... maybe the statuses could be distributed randomly with the stats.
Fractal, TU, and Mitosis... these pieces aren't technically creatures so much as part of the spell.
So maybe they can't be targeted by such spells. The Shambles spell probably shouldn't be able to target a piece of a creature already in shambles either.
EDIT: Actually Fractaling it gives you a hand of creatures that when you play are 0|0. Mitosis will allow you to copy the targeted piece, but the automatic death is a passive effect, so the Piece with Mitosis dies anyways, and the generated Piece dies too. TU would create a piece that didn't have a Core to return to, so it'd die... unless you targeted a Core, then it'd possibly just revert to that creature with missing stats.
... So what happens if you use this on, say, a 1|1 creature and it turns into four pieces? Do half of them end up with 0|0 and die?
The maximum number of pieces would be dependant on the stats. So a 1|1 creature would just be split into 1|0 and 0|1.
EDIT: But then what's the point of targeting a 1|1 creature?