Originally Posted by death_metal_lawn_gnome
togekiss-aerial ace/yawn/extrasensory/last resort
Togekiss' base Attack is A LOT lower than his base Special Attack (50 < 120). Also his nature is Timid which means even less Attack. Taking both factors into consideration, Aerial Ace is no option and should be swapped for Air Slash (75 power, 95 acc, 30% chance of flinching). Note how this becomes 60% with his ability, which is really awesome. Air Slash can only be obtained by using a Heart Scale at the Move Tutor house in Blackthorn City.
Speaking of Heart Scales... Togekiss can learn Aura Sphere by using a Heart Scale. Since Aura Sphere is one of the best moves in the game if you ask me, doing so goes without saying. Heart Scales can easily be obtained by catching Luvdisc at a Mass Outbreak or smashing some rocks. Switch it for Yawn. Togekiss is not a good pokemon for Yawn.
Third, Extrasensory can be swapped for Psychic at the cost of using a rare TM (you can get it at Saffron, Mr Psychic's house). However, Flamethrower, Roost, Thunder Wave, Grass Knot, Water Pulse, Nasty Plot are also all very good options for togekiss. Remember that 4 attack moves isn't always the best option. You have to have some kind of answer to set-up pokemon, status problems and other difficult situations.
Last, if you want some raw power on Togekiss, consider Hyper Beam. This move offers a wopping 225 base power (with STAB) which enables many, many KO's. I remember the first time I took my Togekiss to Lance, he 1HKO'd Dragonite with Hyper Beam at lvl 60. Now that's a much better "last resort"
Hope this helps. If you have any more questions, feel free to ask!