Magikarp Power

The Trope Namer in action, as seen in the first season of the Pokémon anime. James's Magikarp seems to be a useless fish, not even good as an emergency food source. Enraged, James literally kicks Magikarp out of his team... only for Magikarp to evolve into a powerful (and angry) Gyarados. The Water-type Pokémon expert, Misty, has only one strategy against the Atrocious Pokémon: RUN AWAY!!!

Example of:
Magikarp Power