A Choice Scarf is fantastic for a Typhlosion, it really helps preserve HP. Although it lacks the power of a Choice Specs set, it still packs a punch ,especially in sun, at full health and gives you nice speed. And if something switches in which sponges Eruption, that's what coverage moves are for.
Also, I'd also use Fire Blast > Extrasensory in case Typhlosion gets low on health from Hazards, Priority, or faster Scarfers, because Eruption will not have the best power then. Plus, It still packs a huge punch, and Extrasensory doesn't provide that fantastic of coverage either.
Hope I helped! :)
