Well, your goal is to reach level 36, so here are some options...
- Obtain a Lucky Egg (Has a 5% rate to be found from Chancey's/Blissey's)
- Give Blaziken an overdose of Rare Candies (in other words, use all of them on Combusken)
- Make Blaziken hold the Exp. Share at all times
- Train excessively in previous Routes and try to battle as many people as possible that you have registered in your Pokenav.
- Always make Combusken switch in, then out, that way, he recieves Exp. Points for being in battle.