I had two diferent ones (through starting over) I had first Zigzagoon then Poochyena
I know you don't beleive me but I did I used AR walkthrough walls then went to the third town and bourght pokeballs then courght them
oh and when you save birch he gives you the pokemon you used and he gave me Zigzagoon/ Poochyena and yes you do get to keep Torchic/ Mudkip/ Treeko