Love Shower Pitch! is when Lucia, Hanon, Rina and the other mermaid princesses get together and sing. They usually say it at the end of any song they sing. It gathers a great amount of power, produced by a song and then it sends the power to the enemies that the Mermaid Princesses are facing.
In the anime, Love Shower Pitch! is the phrase all the mermaids use, while in the manga, Lucia, Hanon, Rina, and Karen all have different phrases. Hanon has Pretty Sugar Pitch, Rina uses Cool Shine Pitch, and Karen has Cutie Hot Pitch. It is unknown which is the equivalent phrase for Noel, Coco, Sara and Seira.