Is it normal to get challengers you didn't unlock as regular challengers?

I just recently got to a point where I could beat level 15 - 20 and I've noticed that often I get Meatslab as a regular challenger, but I don't see him in any section of the challengers that I unlocked.

I know that sometimes it asks you to battle old challengers that are now retired, like ones from past events and such. I guess it could have you battle some that you might not have unlocked yet, since all you get is the experience and not the regular item drops. I've never tried to go that high myself though, so I'm not sure if that's typical for that range.

The boss battles are usually retired/old challengers, so that's why I'm a bit confused. s:

Hmm, that's true. I'm not really sure then.

Do you happen to know anything about this?

I just got another challenger I don't have at 21, so I guess it's supposed to happen.

Yes it's supposed to happen :)

Okay, thank you for clarifying! 😊

there should be a list here

I don't think it's 100% accurate, might not be complete any more. but it just shows who appears during which quests. it doesn't depend on anything other than what level you're on