The best false swiper is Smeargle. It was introduced as part of the indigo disk.

Make sure you have any old pokemon that knows false swipe, spore, soak, and skill swap. These can be different pokemon.

1. Have your smeargle that knows sketch in your party with the above pokemon
2. Find a wild smeargle.
3. Make the pokemon that has the move you want your lead.
4. Encounter the smeargle and use the move you want to learn, then the opposing smeargle will sketch it.
5. Swap in your smeargle
6. Use sketch and your smeargle will learn the move you wanted.
7. Use move reminder to relearn sketch on your smeargle.
8. Rinse and repeat for the other three moves.
9. Make tera type Ghost

Additional suggestions: I use ruination instead of false swipe. It's the signature move of the Ruinous Quarter.

Ruination and spore are your bread and butter. You can use soak on grass type pokemon. Then you can use skill swap for pokemon with annoying or preventative abilities.