The explanation for Anti-Black Coat is actually rather simple even without Nomura's words.
One needs to just look closely at it and compare it with its counterpart while remembering that this thing is a Dream Eater.
Most Dream Eaters (except some very rare exceptions) have both a Nightmare and a Spirit version.
Since the Anti-Black Coat is obviously a Nightmare, you have to look which its "Spirit"-counterpart is.
Hint: Ansem SoD himself tells you who the Spirit is.
Conclusion:
It is Riku. Riku is Sora's "Dream Eater" Spirit and the Anti-Black Coat is simply the Nightmare Counterpart to him.
Riku has the Spirit-symbol on his back, the Anti-Black Coat has the Nightmare symbol at the exact same place on its coat.
They are the same height and their battle stance is similar.
The great Heartless from BBS Final Mix and Anti-Black Coat have no connection really.
One needs to just look closely at it and compare it with its counterpart while remembering that this thing is a Dream Eater.
Most Dream Eaters (except some very rare exceptions) have both a Nightmare and a Spirit version.
Since the Anti-Black Coat is obviously a Nightmare, you have to look which its "Spirit"-counterpart is.
Hint: Ansem SoD himself tells you who the Spirit is.
Conclusion:
It is Riku. Riku is Sora's "Dream Eater" Spirit and the Anti-Black Coat is simply the Nightmare Counterpart to him.
Riku has the Spirit-symbol on his back, the Anti-Black Coat has the Nightmare symbol at the exact same place on its coat.
They are the same height and their battle stance is similar.
The great Heartless from BBS Final Mix and Anti-Black Coat have no connection really.
