The Yo-Kai Medallium states in its bio on Rhyth, "The one female of the seaweed trio. Wiglin and Steppa both really like her, but she doesn't seem to notice."
A pale green feminine seaweed creature with big dark brown eyes and tiny pink blushed cheeks. She has a dull red ribbon tied around the top of her head to match the pants she wears. Over the chest are white bandages, along with a loose pink jacket accented by white.
Rhyth, like Wiglin and Steppa is an energetic and cheerful Yo-kai. She loves dancing and enjoys it. In tone with this, she says "Yeah!" every time she can.
Rhyth debuts in EP013 along with Wiglin and Steppa, in which they cause Nate to be able to dance when previously was not able to. While initially grateful, Nate quickly curses this new ability when it takes him to the extreme by causing him to dance even in inappropriate situations. Sometime after this, the Yo-kai Dancers give Nate their Yo-kai Medals.
In EP024, Nate summons Wiglin, Steppa, and Rhyth to make Tengloom smile. However, this plan backfires and all of them fall rolling down to a three, which ironically makes Tengloom smiles.
In EP027, Rhyth, Wiglin, and Steppa are seen in Yo-kai-lifornia where they are among the Yo-kai waiting in line for the release of the Yo-kai Watch Model Zero.
"Rhyth" is a corrupted form of the word rhythm.
"Mekabu-chan" comes from mekabu (和布蕪), thicker wakame leaves cropped near the stalk.
"Tschatscha" consists of the word "tscha tscha" which means "cha cha".