Just outside of town

He does study Pokemon right? There are some Pokemon in the tall grass just outside of town. You won't go that far in so it should be safe. As soon as you take a step you hear a familiar voice.

"Hey! Wait! Don't go out! It's unsafe! Wild POKEMON live in tall grass! You need your own POKEMON for your protection. I know! Here, come with me!"

He takes you to his laboratory. You approach a table with three Pokeballs waiting for you

"Gramps! I'm fed up with waiting!"

"Blue? Let me think... Oh, that's right, I told you to come! Just wait!"

"Here, Red! There are 3 Pokemon here! They are inside the Pokeballs. When I was young, I was a serious Pokemon trainer. In my old age, I have only 3 left, but you can have one! Choose!"

"Hey! Gramps! What about me?" Blue cries out.

"Be patient! Blue, you can have one too."