When the Shredder returned from his defeat at the hands of the Teenage Mutant Ninja Turtles and their master Splinter he set out to rebuild his Foot clan and get revenge on the Turtles. After his Foot clan manage to steal the remaining canister of ooze and kidnap the scientist in charge of destroying it,named Jonathan Perry, the Shredder orders his men to bring him two ferocious beasts and they fetch a snapping turtle and wolf who become Tokka and Rahzar when exposed to the ooze by Professor Perry. Though strong beyond count the two mutants have the mind of infants and take Shredder to be their mother. Through his commands they attack the Turtles but are eventually given a chemical which reverses their mutation and reverts them to the animals they once were.
Creation

Tokka and Rahzar were created for the movie Teenage Mutant Ninja Turtles II: The Secret of the Ooze (1991), they replace Bebop and Rocksteady.
Other Media
Television

Animated
Teenage Mutants Ninja Turtles 1987 animated series
Tokka and Rahzar only appear in the episode Dirk Savage: Mutant Hunter.
Teenage Mutant Ninja Turtles 2003 animated series

Tokka and Rahzar appear in the special Turtle Forever (2009).