Eurogamer has some more details on the online for Mario Strikers Charged for Wii:

Most excitingly, it will be possible for two players on a single Wii to play on the same team against two players on another Wii connected to the Nintendo Wi-Fi Connection network. “So [we] could team up on our office Wii and play you and Kristan on your Eurogamer Wii,” a Nintendo UK spokesperson explained.

I cannot wait till we get this here in the States!

Source: Eurogamer