Phoenix Wright, duh. Ace Attorney getting the recognition it deserves would be amazing. There's a lot of creative things you can do regarding his moveset, he'd bring some awesome music and cool stage ideas.

Correct me if I'm wrong but I think he'd be the first playable visual novel character, which if anyone is ever going to get that title it should be him. The franchise is also really popular in Japan :3

For the second fighter's pass, with six characters, if I were allowed to choose those six...

I'd go with the following:

1. Sora (Kingdom Hearts). This feels like the perfect time to bring Sora back to a Nintendo console/handheld, and Sora is one of the most recognizable characters in gaming today. The big obstacle is the obvious Disney and Square Enix BS we will forever be dealing with (thankfully we got Cloud from SE, but that might be it), but Sora would handle really well in Smash Ultimate and may be worth the hassle.

2. Rex with Pyra/Mythra (Xenoblade 2). Ultimately, Smash is still a Nintendo product. That's why it's only on Nintendo consoles. Rex is one of the most prominent new exclusive characters on a Nintendo console, and already has a Mii Costume. While that may exclude him from getting in this go around, it's worth noting that for the first FP, Sakurai only said he was brought into Nintendo too late for "that" Fighters Pass. Gives me a suspicion we'll see him now.

3. Phoenix Wright (Ace Attorney). He's wildly popular in Japan, and he's also pretty nichely popular in America. And we need more wacky fighters you wouldn't expect (AKA Piranha Plant). While his moveset would be tricky to come up with, we've seen Sakurai work with less. His music would be incredible too.

4. Main Character of Astral Chain. Astral Chain was significantly more successful than expected, and could end up launching a new series of games. Additionally, the character's aesthetic would be easy to implement into Smash and it would not take too much additional effort to make the male/female alt work out, given how similar the defaults look. We should reward successful games.

5. Lloyd Irving (Tales of Series). One of the glaring omissions from current Smash is the Tales of Franchise. We have a character from Final Fantasy, from Dragon Quest... and none from Tales of. In my opinion, these are the big three JRPG franchises that need to all be equally represented. As for which character, choosing Lloyd (or Yuri Lowell) makes the most sense, as they are the character(s) that most consider the most recognizable (think Terry from Final Fight).

6. Waluigi (Waluigi). It's Waluigi time! Wah!