The Power of Friends
The Power of Friends (Japanese: ゆうじょうパワー, Friendship Power) is the power of invoked by Starfy's strong friendship with characters like Moe and Bunston in The Legendary Starfy.
Initially, Starfy and Bunston as Monstar could not defeat Mashtooth because he was protected by a large magenta barrier, however, after Starfy lost all his hearts he still stood and did not cause a Game Over. After Moe shouted for Starfy and Bunston, Bunston insisted that Mashtooth would not win and Bunston cried to Bunston for help. Starfy stood strong against Mashtooth and Mashtooth felt a strong power inside Starfy; which was the Power of Friends. Moe then told Mashtooth that the Power of Friends is stronger than anything else in the entire universe, claiming that it is something Mashtooth could never have or steal.
After Starfy defeats Mashtooth, he absorbs Bunston's Powers by swallowing him, and this causes Mashtooth to transform into Mega Mashtooth. After Mega Mashtooth claimed that Starfy and Moe are next to be defeated, Starfy collapsed and fell to the floor but then The Terrible Trio used the The Paper-Cut Crusher against Mega Mashtooth for the sake of Starfy and his friends. Though The Terrible Trio could not defeat Mashtooth and got injured, it was enough for Mega Mashtooth to spit Bunston out.
The Terrible Trio encouraged Starfy to do a Star Spin and soon other friends including Starly, Bunston, Old Man Lobber and Moe encouraged him to get up, with Moe telling Starfy to "sock him for me!". This filled Starfy with so much power, that it gave him a large blue aura and allowed him to fly into the sky to confront Mega Mashtooth.
Normally, Starfy is the one in the main story to fly into the sky and push the moon into Mega Mashtooth, however, Starly can can confront Mega Mashtooth in Big Bossdown, and Starly can be seen pushing the moon in the Starly's Ending Story cartoon, which is unlockable by beating Mega Mashtooth with Starly.
Related power
In Densetsu no Starfy 4, in Degil's Castle, it is implied by Mattel that the power of Starfy's friendship with Moe made it possible for him to be the first person to learn the Powerful Spin.
In Densetsu no Starfy 2, in a way, Numan and Puchi Ogura #5 use this to their advantage, with Numan 'sucking up' the worries of Puchi Ogura #5.