That is a nice indicator, but it has a logical error in it (it inverts the values). See the example comparison : where the values should go up they go down, and vice versa.
Slow Relative Strength Index by Alexander Gettinger
Can this be made the same way as smoothed rsi?
Here you go : srsi_2.mq4
Can it use other average types in the indicator (not just ema)?
Techmac, modified it to use other average types.
RSI with Trend Catcher signal new
What would rsi of rsi look like?
Like this : rsi_of_rsi.mq4