Using the Colour Fade effect, you can change the colours of a part of your scene, such as a character, a prop or a background, to a different set of colours over a specific span of time.
The Colour Fade effect works a lot like the Colour Override effect, except that it has an animatable parameter, Fade, the value of which can go from 0 to 100: At 0, the colours in the image are unchanged, at 100, the colours in the image are replaced by the override colours, and at 50, the colours in the image are an even mix between the original colours and the override colours. Hence, by animating this parameter from 0 to 100, you can create a colour fade effect.
Just like with the Colour Override effect, you can use cloned palettes to replace several colours at the same time with the colours in an alternate palette, or you can select individual colours in the image and replace them with custom colours one by one.