Vs. Recorder
The Battle Recorder is an item exclusive to Pokémon Platinum Version, yet to be released. It was announced an issue of CoroCoro.
The Battle Recorder is likely to be a key item but it is still unknown. It is confirmed that the Battle Recorder can record and replay a player's battles, similarly to the Frontier Pass's Battle Record, and send them over Nintendo Wi-Fi at the new and improved Global Trade Station in Jublilife City. It is still unknown if the player can record online battles or in-game battles.
Modes
There appears to be several features and modes on the Battle Recorder apparently using the Nintendo DS's touch screen to operate. It's likely that there will be a mode in which the player can send and receive recorded battles on Wi-Fi.
Browser mode
The Browser mode is the only mode so far that has been comfirmed. Browser mode does not require Nintendo Wi-Fi to use. It can record, replay and delete battles made by the player or a friend.