Who do tu think should appear in the future.

Casey Jones! Though the creators have already announced that Casey will mostrar in season 2! :D

Also, Beebop and Rocksteady. But since Shredder has Fishface and Dogpound (Love them!) I doubt they'll make a big appearance,

Mona Lisa, Lotus Blossom(80's Show), and Hun(03 Show) for me. Maybe Buffy as well.
I wouldn't mind Venus so long as they give her a decent back story and characterization. Perhaps change her personality around and make her (and keep her) human. She and Lotus Blossom could friends of Karai's from Japan.

I would add Irma from the 80's series as well, but she's already set to mostrar up for season 2.

Bishop (03) will be a nice addition to this. o at the very least, someone like Bishop.

I could probably see Mona Lisa coming in as well.

bebop and rocksteady

Mona Lisa

I would like to see one of the usagis yojimbo o myamoto, maybe lotus blossom (but to me she's just an older as in anterior version of Karai), Mona Lisa, Casey Jones, and Venus de milo(don't judge they could make the character a lot better in this).

None of the above. Splinter's wife should come and make things a bit interesting

Wingnut has already been in the show- April's dad. And I've also heard that Mondo geco, gecko is set to be in it, as well as Flaming Carrot and Fugitoid

Mona Lisa and Mondo Gecko