Yes. Dream World pokemon come with abilities that aren't obtainable in the game. For example, in the games, Dragonite has Inner Focus. but if you evolve a Dratini from the Dream World into a Dragonite, it will have the ability Multiscale.
Dream World Pokémon can also have attacks that they normally couldn't have/couldn't have in Generation 5, such as Spinda knowing SuperPower and Salamence knowing Outrage.