Monster Hunter 3G (Tri G) will not support online multiplayer

While we just get confirmation of RE: Revelations support online play, but Capcom has clarified the online mode question that remains without answer since the game is announced. This game cannot play with other players via internet, however, it uses the internet to download additional quests like PSP's MH does. We hope another 3DS exclusive Monster Hunter title could have this online multiplayer mode in the future.

Here's the official confirmation