Why was Serena written out?

[MarshiyanMisutaa]

There's no need to be so dismissive, geez. And yes, the producers could have been like "these upcoming sequels are more connected to past games, so let's bring these older, fan-favorites back".

Please. Your point was "it's not fanservice, they bring them back to promote games". True, BW2 is more connected to past games compared to BW1. But that itself is no reason to bring back these characters, which as I said had nothing to do with BW2 games in the first place.

I'm not pretending to act like I know what they were thinking, I'm just saying this has always been my best guess on what maybe, perhaps, might have happened behind the scenes.

Why though? There is no reason to believe that PWT or old pokemon-appearing-in-games-again is enough justification for these unusual call-backs and other fan-service related stuff.

 

[Tuoko]

If they wanted a girl that could stay for more than one generation, they'd have to give her a Pokemon that's representative of the series as a whole and isn't tied to any one generation, like Pikachu with Ash.

Only one that could really work is Lucario, especially since it's appeared in every saga since its introduction.

On top of that, the Pokemon that got amiibos (a VERY important selection as Nintendo wants them to sell a lot. They're not your traditional merch. And you can only get a select few 'mins to get one) were the most iconic selection: Pikachu (obvious), Charizard (even more obvious), Greninja (ranked no. 1 in Japan), Jigglybuff (became iconic due to the anime), Mewtwo (arguably the most popular legendary), and Lucario.

These are the Pokemon game freak themselves consider the most iconic, and will promote.

Those amiibo you mentioned are all tied to Smash, and the Pokemon amiibo have had poor treatment. They only have unique compatability for four games (SSB 3DS/Wii U, Mario Maker, and Kirby: Planet Robobot).

Even then, they're still missing other Pokemon (Squirtle/Bulbasaur, Eevee, Meowth, and Wobbuffet to name a few).