Johto
It was her starter Pokémon, 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".
Unlike Jimmy's Typhlosion and Vincent's Meganium, it doesn't seem to be used as often, only appearing once as a Croconaw during The Legend of Thunder!.
Marina uses Wani-Wani after the defeat of Little Pink in the battle between Jimmy and Marina, Jimmy then calls Beedrill back and use your Typhlosion to battle against Water-type Pokémon, Marina shows during the battle to be in sync with Croconaw actions, in the battle despite the disadvantage on the part of Typhlosion, it stands up well to the attacks of Wani-Wani and Typhlosion as he prepares to fight back the attack of the opponent an explosion in the background hangs the battle.
Marina and Jimmy concerned sends his Pokémon back to the Pokémon Center, however misguided they end up going the wrong way and are called back to the Poké Ball.
It had a cameo as a Croconaw in the beginning of the movie Pokémon Ranger and the Temple of the Sea.
Sinnoh
It was revealed it evolved into a Feraligatr during an internet broadcast of a Pokémon Contest in A Stand-Up Sit-Down!. It used Aqua Tail in an appeal round in conjunction with Little Pink during a double performance performed in the Hearthome City.