Suggested ability: Blaze
Eruption-STAB; high power. At full power, this is essentially a blast burn that doesn't require charging. When his health starts to fall, the next move comes into play.
Flamethrower/Fire Blast/Overheat-Flamethrower is the most reliable of the three; overheat is the strongest, but cuts his special attack. Fire blast has the lowest accuracy, but has no other major drawbacks. Go with flamethrower if you want to be safe, but keep in mind that Typhlosion doesn't have time for being safe in most cases.
Hidden power [ice]/[grass]-Grass is there to cover all of his weaknesses at once. ice doesn't offer as much coverage, but gives him the power to tame dragons. Grass is more useful in the lower tiers he typically battles in.
Focus Punch-While this is a special set, Typhlosion can utilize this pretty well, especially if you're gonna risk running him in an upper tier. A Chansey or blissey would be a perfect choice to wall him out, and if you predict that, this focus punch can easily do away with it. An unsuspecting Tyranitar would fall to his 4X weakness. In the tiers we established here, it's pretty useful for taking out a few threats, like the special walling Umbreon.