Is this condition aviable after or b4 I beat the pokeleague?I don;t want to spoil it, but I'll tell you that it is possible to catch ditto under certain 'conditions', one of which being that you'll have to have the PokeRadar.
YES YOU CAN!!!
Here's a lil' guide:
1. beat the E4 and Champ.
2. get PokeRadar.
3. see all Sinnoh Poke's and get National Dex
4. Route 218 (I believe), PokeRadar.
5. after an insane amount of Pokemon, you'll meet a Ditto.
6. catch Ditto.
That's about all.