Made a chart of whether Mega Evolution will be beneficial, detrimental or neither to the Pokemon’s Quality of Life.

This doesn't include Legenda Z-A Megas, because it's not out yet. I made this for discussion.

Red Face = Detrimental

Yellow Face = Neither Detrimental nor Beneficial for life.

Green Face: Beneficial to Quality of Life

Pokemon on the lines (designated with symbols) follow logic outlines in the Legend at the bottom of the image.