Basically, in this form [The golf ball size] It's easier to carry around. You can fit it in a pocket or even on a key chain if you get creative. But this. [And he squeezes to baseball size. He then stands and aims at the center podium in the room and... pitches it like a baseball]

Makes it easier to throw accurately!

[And once it touches down over thee it pops open. this would be whee it releases a pokemon if one's in there. Because none is it just re-closes]