Warlords Combat; Raise the Pokémon to a specific Link % and battle against a Warlords and defeat it.
This method applies to Machoke, Kadabra, Boldore, Haunter, Gurdurr which are the Pokemon generically evolved by trading
The required link percentages are;
Machoke/Boldore/Haunter/Gurdurr - 60%
Kadabra - 55%
Darwin's evolution theory. Nah :P