[He doesn't say anything else when Yuuri asked that question. Instead, he tosses his Poke Ball up in the air, which it pops open and releases a blue energy that transforms into his Mach Pokemon.

Regardless of Yuuri's reaction, Sycamore remained calm as he pets his Garchomp on her snout, much to her delight.]

I think that should answer your question. But I might not able to answer about the Poke Ball's mechanics. Trust me, it's a little bit complicated.