Generation V has made great leaps in today’s metagame with the device of Dream World abilities. These refreshed skills have added a new dimension to competitive play with frailer members managing last longer with Regenerator and Magic Guard, and offensive teams supplied with the means to combat stall in the form of Magic Bounce.
However, the most considerable shift has been the introduction of Drizzle Politoed and Drought Ninetales taking their respective places along side Tyranitar, Hippowdon, and Abomasnow. These two have made all forms of weather viable in OU and have impacted other Pokemon, including the now Solar Power Charizard and Chlorophyll Venusaur.
Though, there is a dark side to the Dream World. A few of the new tricks provided by Gamefreak have been game breaking - launching Speed Boost Blaziken into the Uber tier along with the aforementioned Politoed used in conjunction with Swift Swim.
In conclusion, these abilities may have their downsides (or lack of, for that matter), but collectively they have reinforced the game and dusted off our old Gold and Silver veterans for round five, and for that we should be thankful.