Yes I agree with the thought of making it grey and then adding color in engine. I think that might help me get my render time reduced since I am struggling a lot with it. Also, I did try out shading the pyro and got hang of it quite easily(Didn’t expect that 
).
Can anyone guess why the pyro takes so much time to render out and doesn’t properly give spritesheet while doing mosaic output ? 
Thankyou for all the solutions. Really appreciate it. 