Lets look at Dratini:
R/B: Eww! Looks more like a worm.
Gr: Still looks like a worm but its ears/horns look better.
Y: What the heck is up with its colour?
G: I don't really like that position.
S: I like it. It's a cuter and improved version of its literally Yellow sprite.
C: Its colour is way too pale.
R/S: Worst Dratini sprite ever! Its colour is all wrong and its snout is too big.
E: Why are most Emerald animations so boring?
LG/FR: Poor Dratini, always having its colour wrong. At least its snout is smaller.
D/P/Pt: Now that is perfect. They got its colour right this time.
HG/SS: Why do most pokemon look anorexic in HG/SS?