Instructions
Head to Violet City through the Dark Cave. Your rival will stop you as you get to the gate and give you the Vs. Recorder.
Start a battle over Wi-Fi or at the Battle Frontier.
Finish the battle and you will be asked if you want to save the battle using the Vs. Recorder. Select Yes.
Select the Vs. Recorder from your "Key Items" menu to open the recorder interface.
Select "Browse Mode" to view your stored battles. You can also view your Trainer Ranking and Battle Video Rankings here.
Go to the "Global Terminal" on the second floor of any PokeCenter.
Go into the Blue Room to view the top Trainer Rankings and the Battle Video Rankings.
Go to the Green Room to view other players' "PC Boxes," which contain Pokemon. You can upload one of your own PC Storage Boxes for others to view.
Go to the Pink Room to upload your battle videos to the Wi-Fi network. You can also view other players' battle videos. Your video will be assigned a code you or your friends can use to search for it later.