"The Man of Yesteryear said:Bulbapedia:"I'm not even sure Ditto can turn into Kirby since Kirby isn't a Pokemon..."
actually ditto can turn into anything even inanimate objects"
Ditto is capable of Transforming in to an an exact replica of any other Pokémon (an ability that is also shared with Mew), or indeed any physical object. However, if Ditto tries to transform into something based on memory, it may get some of the details wrong. Ditto will also be unable to remain in a transformed state if it starts laughing. Frequently, a Ditto appears that can't transform its face. This fact is seen in the anime, as well as in Pokémon Snap (in which several Ditto are transformed into Bulbasaur), and Pokémon Diamond and Pearl (in which, during the Game Corner slot machine game, a Clefairy with a Ditto's face will occasionally appear instead of a real Clefairy). In rare cases it will lack the ability to increase or decrease in size, thus rather than creating exact duplicates, it will create (usually) miniature versions. Ditto can not mimic the strength of another Pokémon. Ditto's ability to breed with any non-legendary Pokémon is also useful for creating Pokémon eggs of the more rare Pokémon that it may be difficult to get a mate for, such as the starter Pokémon.
"Ditto still loses even if he can transform into Kirby.That's Wrong Ditto has proven it's stronger then the orginal, and it can turn into inanimate objects.
He isn't as experienced and I would guess the power Ditto copies aren't as powerful as the original's."