This info was originally posted by darthatron.
So, each sprite has a limit to what it can contain...
Battle Sprites:
* Must be <=16px (32px for monsters) wide and <=40px high.
* Must contain 15 colors or less (+1 background color). See below for useable palettes.
Portraits:
* Must be 64x64px (needs verification)
* Can have up to 47 colors (+1 background color).
And the Big question is " How do you replace the custom sprite in the game? "
exactly, is it the typical old school tile editor because that is a pain...