When it comes to Super Smash Bros. roster selection, fans have many theories on how different characters end up in the games. Some of it is mixed with actual facts we've heard in the past, such as how a Pokémon from the latest generation is guaranteed a spot by Nintendo mandate. Others are based on reasonable speculation, like how Pac Man was probably the result of Bandai Namco's development work on Smash 4. Joker of Persona 5's inclusion as DLC is more of a mystery, or at least it was until now. It turns out Sakurai just asked for him.
ATLUS director Naoto Hiraoka recently made an appearance at the Taipei International Video Game Exhibition. While he was mostly there to promote Catherine Full Body, he spoke to GNN about Persona 5 and Joker's upcoming appearance in Super Smash Bros. Ultimate. Through a combination of awkward Google translate and Reddit user lancelam, we were able to learn more about the process behind the Smash roster.
"Joker joining the roster in Super Smash Bros. Ultimate is mainly due to invitation from Masahiro Sakurai (Sora Ltd.)," reads a translation of Hiraoka's statement. He goes on to say that Sakurai "likes Persona 5 very much, and I happened to like Super Smash Bros. very much. So, when (we) received the invitation, the first thing we thought is 'Great!'”
The important thing to note about Hiraoka's version of events is that it makes the choice sound simple. Sakurai likes Persona 5, so he wanted to put a character from it in Smash. That's all it was.
Fans can often read too much into a character's inclusion. In this case, many took Joker's addition to Smash as a sign that Persona 5 would end up on Switch in time for a cross-promotion. The logic is not entirely unfounded. Again, Nintendo makes Sakurai include a Pokémon from the newest games in order to promote them. Unfortunately, there does not seem to be such a conspiracy behind Joker.
That doesn't rule out the possibility of Persona 5 coming to Switch after the fact, however, as a reaction to fan demand. When asked about that, Hiraoka said that he could confirm nothing, but called the Switch a "very attractive" console.
On a side note, my new favorite thing is that Google translated "Super Smash Bros" as "Nintendo Star Wars."