So I’ve been unlocking characters regularly doing just the traditional Smash mode. I got to 51 characters, and now no more character unlock opportunities are happening.

I read that you have to try different modes like classic mode to keep unlocking, but classic mode beaten with multiple characters, squad strike, and tourney mode have not worked.

I haven’t had a character unlock opportunity in like 4 hours! What’s going on, and why does this game have to be so damn enigmatic rather than just being clear and telling you?

Have you tried Spirit Mode???

World of Light?

I'm not done unlocking but what I do is play regular mode and after one or two games I unlock a character. Then restart the game because the average is every 10 minute for a new character so if you restart the in game timer goes away.

wait... you've unlocked 51 of them, did you fail to unlock others? you know they are waiting for a rematch for you in the top right area of the main menu... it's called something like challengers await, it's a rainbow coloured gate in the bottom right corner of the section called "games and more" sorry had to open my copy to see what the section was named.

Let me know if you have that waiting for you.

(just going to point out, the game did tell you about this, you just failed to read it lol, that's not the games fault, except for being too fun for you to stop and read a screen of text tips! also keep in mind that smash has over 60 characters unlockable by playing the game for a few days, Street Fighter V takes months to unlock 5 characters from those season passes, or you need to pay around 30e per 5 characters)

Try checking Challenger's Approach. It's under Games & More.

How about Piranha Plant? Should he be available after registering or do I have to unlock him first? Because I can't find him and wasn't sure if that's normal or not?

Ah, that was it! No wonder I couldn't find him, I'm relieved now, thanks!

Sorry, I tried to reply last night. But this site is so insecure that I’m constantly being redirected to a “Congratulations Amazon.com user!....” page. Was barely able to create the thread. 

Anyway, your response was the big winner. I had no freakin idea that section existed. When did they tell me that?? Haha:/

Followup question:  I did all my rematches and I AGAIN lost three of them. But the section for rematches is gone, and I again am not getting “new challenger” opportunities. Any idea how to unlock them now? I think I have 66 unlocked. 

Ahh, 71 makes more sense. I also read an article that suggested Pokemon trainer counts as 2 or 3 characters? Is that true?