Box art leaked the fact that Sonic’s stint in King Arthur’s world will take advantage of Nintendo Wi-Fi. Will it be for online sword duals between Sir Sonic and Lord Eggman? Maybe not.
Details from a product listing at Rakuten explain the Nintendo Wi-Fi Connection feature will be used for ranking and item trading. Sonic and the Black Knight has 200+ items to collect. If you can’t find all of them you can always trade your way to the Excalibur or whatever legendary sword Sonic uses.