After players beat the mainline story events in Pokemon Sword and Pokemon Shield, there are multiple new aspects of the games that players can gain access to. One of these things is the Battle Tower, where players can earn BP in exchange for various rare and helpful items.
Players will know if they have access to the Battle Tower in Pokemon Sword and Shield if they are contacted by Leon about it. Then, players will be able to travel to the old location of Rose Tower, which has been converted into the Battle Tower.
With the BP earned at the Battle Tower, players can exchange it at the two BP Shops located in the Galar Region. The first is located inside the Poke Mart in Hammerlocke, while the second BP Shop is located inside the Battle Tower itself.
Each of the BP Shops have their own supply of helpful items that players can use to help their Pokemon. Some of these items include nature changing mints and evolutionary items for Pokemon such as Dusclops and Milcery. Players wanting to buy in bulk, however, will need a good BP supply at their disposal.
The Battle Tower is one of the main methods player have for obtaining BP. The higher a tier the player reaches in the Battle Tower, the more BP they will earn as a prize.
Players at the Beginner tier will get only 3 BP as a prize, which isn't enough for any prize available through BP Shops. Reaching the Pokeball tier, however, will bump the received BP to 5. After that is the Great Ball tier which offered a good jump in BP amount, as it will give players 10 BP. Players are then able to get 20 BP by reaching the Ultra Ball tier. If players do well enough in the Battle Tower, however, and reach the Master Ball tier, they will get 50 BP as a prize.
Although the Battle Tower is how players will get the majority of their BP, there is another way to obtain it. This is only available however for players that also own Pokemon HOME.
When players store Pokemon in Pokemon HOME, they will earn Pokemon HOME points. These points can then be converted into BP at a rate of one BP per thirty Pokemon HOME Points that can then be transferred to either Pokemon Sword or Pokemon Shield.
Pokemon Sword and Shield are available on the Switch.
Source: IGN