Carter was taken aback by this new girl's forwardness and curiosity. He smiled, though, and opened his Dex for her, pressing the main catalog button. It popped up a list of all previously scanned Pokemon, and left blanks in the empty spaces.
"This is a Pokedex. It's not a Pokeball, or anything. It simply records data." He clicked down through the short list of his known Pokemon. "See? Basically I can just scan a Pokemon and it will give me information on that type. As for your other questions... Well, you could probably get one from Professor Oak. That's who gave this one to my dad, who gave it to me. And What I think you're confusing this for is a Pokeball." Carter said, taking a couple of the red and white spheres out of his bag. Currently there was only one on his belt, for Teddiursa. The balls were a little bit bigger than golfballs, in passive mode. He clicked the button and they expanded to the size of a softball. "See? It uses pocket dimension technology to store a Pokemon in a safe environment." He handed her one. "You can have that one. It's empty, but you can use it to catch a Pokemon."
"Do Pokemon go away after you make friends with them? Hmmm... I don't think so. Teddiursa's never wanted to leave, right buddy?" Carter looked down, expecting to see Teddiursa, but he and the girl's Azuril had run of to meet the other Pokemon. "Ah...what I meant was, even if your Pokemon aren't with you on your journey, you'll always be friends with them." Carter smiled, satisfied with that answer.
"What else did you want to know?" He thought for a moment, counting off her questions on his fingers, and then he nodded. "Right. 'Do trainers have partners?' Of course! Every trainer is the partner to their Pokemon. The more Pokemon you have, the more friends you have, and the more partners you have! If you're good friends with your partners, you become a strong team! Unless you meant, like...other trainers as partners." He looked around at the group. "It's the same thing, really. People can partner up with each other, like people and Pokemon. The better friends you are, the better partners you are." He grinned and offered his hand. "Speaking of which, I'm Carter Dane. Maybe we can be partners too?"