Reported by Serebii:
-Character customization features six base models to use. Poké Coupons can be used to buy accessories and clothes beyond the basics, and upon clearing a challenge in the game, you can use the Lucario suit that the mysterious Colosseum leader wears.
-A "Midnight Colosseum" has been revealed. It is thought to be used for the highest level battles (Prime Cup/Orre Colosseum, perhaps?)
-At the beginning of the game there are ten Colosseums. No word on if there may be more hidden.
-Free Battle teams can be saved to the Wii Remote for easier transport if you don't carry your DS. Neat little feature, if you ask me.
-Wifi is done in two styles: you can either battle with friend codes ala DP, or be matched against an opponent of equal skill level anywhere in the world---and it isn't download-based like the DP Battle Tower either, as you will be matched in real time.
He's also added lots of new pics, showing GORGEOUS new graphics with Pokémon like Berobelt, Mukkuhawk, Jibacoil, Dialga, Palkia, Floatsel and Rentoraa.
(Original source of pics: http://www.dengekionline.com/data/news/2006/11/30/9377a9f499b02d87306e305e53a8d749.html)