Why isn’t my pokewalker connecting?

Question

So I recently bought a pokewalker from eBay and idk how to reset it but but when I get to the connect the pokewalker it jus tells me to choose a Pokémon and there’s already a Pokémon in it from another game does that mean I have to reset my game to use the pokewalker or is my game fake?

Answer 1

As long as a Pokémon is on the Pokéwalker, the specific game it came from is locked to that Pokéwalker, and it will only send back to the same save file.

source
I guess you'll have to delete that Pokemon unless you somehow find the save file it came from.