Wani-Wani was obtained as a Totodile from Professor Elm on the same day that Vincent received his Chikorita and Jimmy received his Cyndaquil, as seen in the Japanese opening and ending theme "A New Oath".
In The Legend of Thunder!, Marina used Wani-Wani to battle Jimmy's Beedrill after Pink was defeated. Jimmy then called Beedrill back and used his Typhlosion to battle the Water-type Pokémon. During the battle, Marina was revealed to be in sync with Wani-Wani's actions. Despite the type disadvantage, Typhlosion managed to stand up to Wani-Wani's attacks.
However, the battle ended without a winner being declared because Marina and Jimmy ended up seeing from a distance the change in climate caused by Team Rocket's attack on Raikou. Shortly afterwards, Wani-Wani was returned to its Poké Ball.
Wani-Wani made a cameo appearance along with its Trainer in the beginning of Pokémon Ranger and the Temple of the Sea, where Marina and her Pokémon were seen running in a plain as a Lugia appeared next to them.
Wani-Wani was revealed to have evolved into a Feraligatr during an Internet broadcast of a Pokémon Contest in A Stand-Up Sit-Down!. It was used alongside Pink in a Double Performance, during which it used Aqua Tail to lift Pink in the air so the Balloon Pokémon could use its Psychic attack to splash the water.