Super Smash Brothers Ultimate - Rex's exclusion in a nutshell (As far as the base game and the fighters pass are concerned)

2015

Nintendo: Hey Sakurai would you please make another Super Smash Bros. game for the Nintendo Switch.
Sakurai: Okay. Any future titles I need to know about?
Nintendo: Nope, just a new Mario and Zelda game.
Sakurai: Okay.

2016

Sakurai: Okay the rosters almost finished anything else I need to know about?
Nintendo: Well, there's Pokémon Sun and Pokémon Moon, also Luigi's Mansion and Yoshi's Woolly World are getting sequels.

2017-2018

Nintendo: Announces ARMS, Splatoon 2, Xenoblade Chronicles 2, Nintendo LABO and whole slough of unique and original Nintendo games before Super Smash Bros. Ultimate was announced.

Sakurai:
Am I a joke to you?

Shulk: If you throw us your clothes maybe you can run faster!