On day 5 there will be a PNF new flash about the Anime 5 Disc. Professor Oak says that magnemite won't be able to find it.
You need to have a Mt. Snowfall pass for this. Take the bus to Mt. Snowfall. Keep moving to the right until you stop. There will be a signpost. Click on it. Once you're in there, there should be a Gengar. Click on it.
It will say you need the Duskull Lamp. Leave the Ruins of Truth and go to Springleaf Field. Say hi to the Duskull. Answer the question correctly. Instead of a Nice Card or P10 you will receive the Duskull lamp.
Go back to the Ruins of Truth. Click on the Gengar. He should flee. Enter the building. When you get in you'll see 2 dots. Click on them. Pikachu will shock them and they will light up and a sign will appear. Click on it. You'll be brought to a tomb stone. Click on it. You'll be asked a question about Pikachu. Click the "X". The tombstone will be switched with a Golbat statue. Click on it. Pikachu will get stuck. Jiggle the control stick until Pikachu comes out with a disk.
After you get out, a Magnemite will take the disk. Now you can watch Anime Part 5 whenever you want.