Original: PokÃ mon Pinball has a secondary objective hinted at by the tagline "Got/Ota Catch'em All," which is to collect all 151 PokÃ mon to fill your PokÃ dex. The PokÃ dex is saved between individual games, so it can be built up over time.
Simplified: It's a pinball game based on PokÃ mon Red and Blue, and like those games, it requires the player to find and capture all 150 PokÃ mon to fill the PokÃ dex.