I want a Typhlosion so badly!
First, you have to complete the main story. Next, go to Whiscash Pond. Make sure you are by yourself. Nobody can be with you, not even teammates. Next, you will be able to send a pokémon into Luminous Cave. This is where it tells you what you need to evolve if you can't. In this case, you need to be level 14 to get Quilava, and then level 36 to get Typhlosion. Also, make sure the pokémon you want to evolve is the teamleader.
Read this if anything was confusing.
Hope I helped!