Namco Bandai and Tekken series director Katsuhiro Harada have made a deliberate effort to include as much free DLC as possible with Tekken Tag Tournament 2. Naturally, that includes their online network.
As such, World Tekken Federation (also known as WTF)—the online stat-tracking social multiplayer component to TTT2—will be free for anyone who buys the game.
Although the press release isn’t completely specific about the terms, we’ll have to assume that the free online network access includes everyone who buys a used copy second-hand.
Normally, a developer/publisher has the right to charge for online play in their games, with free vouchers only included in “new” copies of their titles. For people who heavily invest in multiplayer via PSN or Xbox Live, but prefer to buy used games, it’s not a choice that particularly sits well with them—so Tekken fans should be satisfied.