to fight the next gym. Your chances increase with the number of Pikachus you have as well as their level, but decrease with the amount of gyms you've already beat. Each gym badge reduces the time it takes to create more Pikachus.

to level up your Pikachus. All of your Pikachus will fight one another until only one remains, him being the strongest of the bunch. Will give you more levels the more Pikachus you have. Each level increases the effectiveness of Pikachu production.