Why didn't the non-Gen 1 character appear in the Gen 1 throwback episode? So mysterious~ D:
Seriously, it's not rocket science, folks. He was from that weird middle period that hardly anyone liked or watched all the way through.
Plus, the whole point was to bring back the two most beloved characters that hadn't been seen or mentioned in ages and Tracey doesn't fit the "beloved" part in any part of the world. The majority either is neutral to him, doesn't care for/about him, or outright hates him. Then you have his tiny 5% fanbase out of the group.
Of course he didn't show up. There was no need for him before and there's no need for him now. Not yet, anyway.
That and we already had Ash, Misty, Brock, Delia, both Oaks, the Alola crew, Team Rocket AND Jigglypuff. Crowded cast is crowded as is. They probably couldn't fit him in. lol