Okay, a Ditto comes deep into Whirl Islands. He sees Lugia and transforms into it. Then it flies out the tunnel again. When Suicune and Entei see that, they think Lugia has turned bad (because it's purple) and they kill it. The transformed Ditto falls down dead in front of Bell Tower in Ecruteak City. Ho-Oh tries to resurrect it, but it fails. The body splits in two, just like the purple color. And then there are two new Lugia's a blue and a red one.