As many of tu probably already know, for a time on your copies of diamond/pearl/platinum tu could have recieved a pichu coloured pichu. If tu did recieve that pichu then tu could get a spiky eared pichu por trading it into a copy of pokemon corazón gold/soul silver. To do this -

1. First play the game up until after the segundo gym. Trade in your pikachu coloured pichu and make sure it is first in your party
2. Go left out of Azelea town and into Ilex forest.
3. If tu haven't already then help out the boy and catch the Farfetche'd. He wil give tu the hm cut.
4. Teach the hm to one of your pokemon and cut down the árbol near to where the guy tu helped was standing.
5. Walk up that way and watch the event unfold...

The pichu tu get with this event cannot be evolved however it has some interesting moves that tu wouldn't normally expect a pichu to learn.

DON'T WORRY!
If tu accidentally evolved your pikachu coloured pichu the event will still work.

HAVE FUN! =D