You will receive a pokemon in real life: this pokemon can do anything it can normally do in the games and anime, and will be loyal to you despite not having a pokeball. Although it will be the only pokemon in the entire world, people won't freak out and they will act like it's something interesting but not absurdly crazy, to the point of calling the police and so on.
If it's not fully evolved, it will evolve by feeding it and taking care of it.
To receive your pokemon, go on
https://randompokemon.com/
generate one single pokemon, and check the nature box too. This will be your companion and there are no re-rolls, you get what you get.