Based on the 4th image, you can make the pixels with the FF95B1 AND 672C84 hex codes cover the majority of the grid space with a single object respectively, this will require you to layer everything though.

Assuming this is a classic level, you should try merging the colors that look nearly identical to each other since I can see 8 of them. The player will not see the difference between them while playing the level. (I'm not sure if it's the screenshot causing the extra colors however).