Is Dusknoir Kaiba?
Given their rivalry in the special, yeah. Though it would've been great if Dusknoir was voiced by Eric Stuart to complete the joke.
According to Bulbapedia he voiced a couple of Pokemon during his Pokemon run
Yeah, like Ash's Treeko conveniently. Even the Zangoose from the special.
Yami Grovyle vs Seto Zangoose
Pretty much! XD
Then perhaps, Dusknoir is Yami Bakura :3