So I got the torchic gift in pokemon x and y, and he has boosted exp (I'm assuming that this is because he's considered "traded"). Is there any way I can make him gain exp at a normal rate?
Unfortunately the Pokemon is considered 'traded' if the Trainer Name/Trainer ID & Secret ID does not match your own.
You can breed it with a Ditto by placing both Pokemon into the daycare, collecting & hatching the resulting Egg, and instead raise the child (which will have your Trainer values). Unfortunately it is male - if it were female you could breed it with any Pokemon in the Field Egg group.
Otherwise, you could try restarting the game countless times in order to try and randomly get the correct Trainer ID, although the odds of getting the exact values is like trying to win the lottery. I don't recommend you try this.
No, there is not. (Theoretically, it might gain XP normally if you managed to start a game with the same name, Trainer ID, and secret Trainer ID as the Torchic's OT, but the odds of getting the last two variables to align are 1 out of 4294967296, and even then there might be some flag that still makes the game treat it like an outsider.)