Meidou

From the Super Mario Wiki

Meidou is a mermaid boss in the NES version of the game Wario's Woods. She has blue hair and a red tail. She wears a crown, but it is unknown as to whether she is the ruler of anything. She has the ability to temporarily freeze Toad's fairy helper, Wanda, during battle. She looks a lot like a mermaid boss from the SNES version of Wario's Woods, Aqualea.