Most of the time, infernape MUST have a + Speed nature as there are a lot of fast and hard-hitting sweepers this generation and infernape must be as fast as possible because it's too frail to take a hit. Unless of course you are training one specifically for the tower...
So a physical moveset would be:
Infernape @ Life orb/Choice Band
Jolly
252 Atk, 252 Spd, 6 HP
- Close Combat
- Flare Blitz or Blaze Kick (if you don't like taking recoil damage)
- Thunderpunch/Stone Edge
- Swords Dance/Earthquake/U-Turn
Pretty Standard. Thunderpunch hits gyarados harder and it's more reliable, but stone edge can hit salamence as well. The last slot is mostly filler. Choose SD if you are going with life orb and have good predicting skills and can predict a switch, earthquake if you want to hit other fire types and electivire or U-turn if you like switcing out with style...
Most people choose life orb and flare blitz because infernape can't take a hit anyway and it's better to be able to change moves.
Infernape makes a good special sweeper as well.
Infernape @ Life orb/Specs
Timid
252 SpAtk, 252 Spd, 6 HP
- Flamethrower
- Focus Blast
- Grass Knot/Nasty Plot
- Nasty Plot/HP Ice
Again, pretty standard. If you can have HP Ice you should want to put it there somewhere and the last slot is again based on preference and predicting skills. If you can predict a switch go with NP. If you can't or if you want to hit swampert, milotic, suicune, slowbro, slowking and rhyperior go with grass knot.
And last but not least... THE MIXNAPE MOVESET!
Infernape @ Life orb/Expert Belt
Naive
252 SpAtk, 24 Atk, rest in Spd
- Close combat
- Flamethrower
- Grass knot/HP Ice/Thunderpunch
- Nasty Plot
24 Atk EVs are enough to OHKO Blissey. Nasty plot on a switch and then start causing chaos. The third move is filler. Grass knot for bulky waters, donphan, rhyperior etc., HP Ice for dragons or thunderpunch for gyarados.