>A traded Pikachu will also not behave like the starter Pikachu, acting as a regular Pokémon instead (even to the point of being able to evolve with a Thunderstone), unless it matches the Original Trainer and Trainer ID number of the player.
Another Pikachu with the same Original Trainer and Trainer ID number as that of the player can be obtained by cheating. However, it will only behave like the starter Pikachu if the original one is released. Furthermore, if one of the new Pikachu is released, the Pikachu behaving like the starter will have a disappointment face for a limited period of time.
The above pretty much sums up my answer.