My Pet Monster

Okay. So I've seen there was Max has a sister Jill Smith (unlike Lucy from Kitou), finally there was swimsuit scenes in the third episode "Boogie Board Blues" Earlier I've seen screenshots of her in swimsuit somewhere, and here it is. That's a whole 20 minute beach episode for the whole time! Jill's best friend Annie (who unfortunately appeared twice in this and a previous episode) also has, among others in background. Jill's swimsuit secondly appears in "Little Bigfoot".

Stanley

Well the series had been found entirely, so the twins Marci and Mimi has appeared in two episodes "Frog Legs" and "There's Snow Place Like Home", others are "Sunburn Stanley" and "Pearls of Wisdom"

Rugrats (1991)

Oh, this is a Nicktoon featuring babies. So here.

Angelica Charlotte Pickles: "Beach Blanket Babies", "The Inside Story", "Driving Miss Angelica", "Cool Hand Angelica", "Mother's Day", "Vacation", 

Lillian Marie Jill "Lil" DeVille: "The Big Flush", "Vacation", 

Susanna Yvonne "Susie" Carmichael: "Cool Hand Angelica", 

"Kimi" Watanabe-Finster:

Other/background characters: "Cool Hand Angelica", "Let It Snow", 

"Beach Blanket Babies"

"The Inside Story"

"The Big Flush"

"Driving Miss Angelica"

"Cool Hand Angelica"

"Mother's Day"

"Vacation"

"Let It Snow"