This is a very simple suggestion, may not take very long to do but will greatly improve the look and feel of custom profiles.
I realise some of the older pets, namely kioka, have white pixels along the lineart that make them look bad against differently coloured backgrounds. These "pixelly" lines kind of make an expensive pet look cheap against a background that isn't white to conceal them.
I don't think retired CS are lined up for revamps, but if this small problem could be addressed I'm sure many would appreciate it.