Well I wasn’t expecting this but I asked how he did it last night. He told me the following.
Gengar: transferred from Red to Silver. He used something called a transform + Sketch glitch. He did this via calling transform from Metronome that Gengar learns via TM in Gen 1. He used the trainer house to find the Smeargle and Lugia.( I think he hacked the trainer house, just saying).
That’s what he said it may be wrong.