There are many creatures in BG2 haven't separate animates, but use other creatures' animate by changing the color. Just like Blue Dragon, Green Dragon and Glabrezu in green in WK. So, I wanna know how to realize these? For example a Black PitFiend. Or, these color changing animates are hardcoded in the exe file?

Yeah, most of these is hardcoded: ooze, wolf, dog, bear, dragon, spider, etc.

I think you can emulate this by applying a coloring effect to the CRE (by spell or item).

Thank you. I'll have a try.

You may wish to check my chromatic dragon in TS. It changes colours.

Yeah, coloring effect does work.
"Change colors by RGB" and "Shinning colors by RGB" can do that.

I think there was an established route for this whereby you could change their colours using magerobes set to different colours. Never tried it though.