Mostly, I must code my own indicator to be used in my ea. Although, mostly my EA use some knd of lgorithm, it is faster or easier to the cpu to subtitute it with an indicator at non critical part of it.
In case someone wonder, only ea that use some kind of algo has stable performance in the long run. Once, I try every standard indicator and the popular strategy avaliable on 3 year data. The only one who ended in positive profit are only the MAs, only small profit. And yes I use filters, event session filter(time). The data are split into 2 period for optimizing and simulation. The funny thngs is if you reverse the ondition (sll vs buy) on stoch, on some period using multi tf it do generate decent profit.
But my conclusion is only algo which deserve to invest your time. Btw, my favorite indicators are iHigh, iLow, iClose, iHighest, iLowest, iVolume, and iATR.