Seriously, Bulba and the anime itself have no mention of Genesect appearing in Episode N. The finale is all about N and Reshiram.
There was something on Bulbapedia, but it basically went like this:
"Corless looks down at his digital pad, presses a few buttons, Genesect's specs came up, Corless smiled." There were supposed to be clips from the movie added in as a sneak peek. I think that was Japanese advertisement only though. I don't think the episode actually air any of that and it was posted in some magazine.
I don't recall seeing it in the actual Anime but it could be one that hasn't aired yet too. But Genesect himself isn't in the anime. Just like they didn't bring Brock and Misty back during the Kanto fair, they were just redrawn memories.
I don't think it was in the final episode though. I definitely want to watch this one though. N using the stone and awakening Reshiram. Seems like an appropriate end. The Anime starts off with Zekrom and ends with Reshiram.