From Bulbapedia, the community-driven Pokémon encyclopedia.
Generation V is seen as a major departure point for the series. While the Generations preceding it often adhered to the formula [[Generation I]] had established, Generation V did several things that differed. Setting itself in a region where Pokémon from previous generations could not be caught, putting out dual sequels instead of a single third version, and using a dynamic camera angle with continuously animated Pokémon sprites in battles. While some of the changes seen in Generation V may have influenced future titles, [[Generation VI]] saw further changes, thus establishing with fans that each generation from this point forward could contain features unique to that generation which may be dropped in then next. Generation V for example is the only generation to date that utilizes [[season]]s.
At the time of its release, Generation V was controversial among the older members of the fandom, mostly concerning the Pokémon introduced. The large amount of Pokémon released caused the competitive scene to shift drastically due to power creep, and Generation V Pokémon were also criticized for their designs. After a while, Generation V came to be considered one of the best Pokémon generations at the time, with more focus on story and characters, and improving mechanics in early game design, such as making TMs unlimited to use.