Not a big cheat but due to the current mechanics of special attacks it is always best top open a fight with a special attack when fighting other Pokemon in the gyms either for prestiging your gym up or beating other gyms down.
You will often waste charging an attack if done too soon after an auto attack and will have to charge again to fire it off. The recent gym battles I've had hang in the balance of just 1 attack, which this delay will cost you. You will also gain more prestige for your gym when progressing further into the lineup when fighting a gym of the same team as you (you may even fight against your own Pokemon there, like I did today) so it can be vital to maximise your output.
By repeatedly holding the special attacks one after the other it will guarantee you will open every fight, bar the first fight, with a special attack as often this can be difficult to execute directly mid fight.
Once the first, and ever other subsequent, Pokemon is down, hold, release, hold, release, hold, release until the fight is opened with a special attack then go back to tap spamming.
Soj