Teenage Mutant Ninja Turtles 2012 is the best, but here this: If the show was made and premiered on Disney Channel, I would definitely revived for Season 6. But, I must accept it as a Nickelodeon show.
So this is what I have in mind for Season 6.
Donnie makes Metalhead 2.0, Mutagen Man returns and Donnie have the retro-mutagen made to turn him back into Pulverizer, Snakeweed and Spider Bytez returns and face April, Casey, and the New Foot Clan for the first time. The Kraang will return and made another lab with the same animal and plant DNA, that was seen The Alien Agenda, and have test subjects to turn them into different animal and plant mutants. And there will be two villains that will become a stag beetle mutant and a spider mutant. New characters will appear and one will have the ability resurrect people without zombifying them and/or controlling them like Kavaxas did to Rahzar and Shredder. Which means that Splinter and Tang Shen will be revived. Fishface and Baxter Stockman will return, but Baxter Stockman will once again become Stockman-Fly. Tiger Claw will also return and with them help from a new character, he will have his arm and tail back and he will no longer wear the eye patch. And last but not least, Alopex will return so she’ll become a member of the Mighty Mutanimals.