Some example of good design is from Heartcatch and Yes 5 go go.
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Simple streamlined designs for their time. For the top, the director of the season apparently worked on Shonen anime before Heartcatch and it shows. The characters have that look with very simple, but cute designs. They have good choice for the color palette and they all feel different without coming off as samey. It has a clear flower inspired look, but it doesn't feel overly complicated (not saying I don't like those designs, but too much is not a good. Thing. With Yes 5 Gogo It's the same thing, only with a butterfly motif minus the last character. Each of the characters have the same look, but it doesn't feel too samey.
That can not be said for the original Yes 5 team:
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I didn't make the markings on these ( it was the only image with all of them I could find easily) but yuck. They look super outdated. I want to cut them some slack considering this was their first team of 5 cures, but it really looks bad. All the characters have their own colors, but that's completely mitigated by the overwhelming abundance of white and a that god-awful yellow tint. It's probably harder to see here, but every character has an awful yellow tint to their design. Why the designer though this looks good I have no idea.
I feel that each character has some sort of awfulness to their design, but I feel cure Mint (the green one) got the worst of it. Not just an ugly hairstyle, but having so much of a mix-matching of green that it looks off-putting.