Ups Speed gain, but lowers Speed.
Power Anklet is for Speed EV training. When your Pokémon defeats an opponent while holding this item, all party members that gain EVs (including Exp. Share holders) receive an extra +8 Speed EVs. The irony of it reducing Speed while training Speed.
Speed EVs are crucial for fast sweepers who need to outpace threats. **Important:** The bonus only applies if the holder defeats the opponent—switching loses the bonus.
Game:Polished Crystal