The First Mention Of The Power Of The Stars
So we all know about the Power Of The Stars, the magic power that comes from Power Stars. By extension is the Star/Wish Magic that plays a major role in the Mario World.
While it gets mentioned in many games like the Super Mario Galaxy games, and most people will recognize the phrase being from Super Mario 64. It actually wasn't first mentioned in SM64.
It was first mentioned in BS Super Mario USA, the sequel/direct follow-up to Super Mario Bros. 2 USA. In this game the King of Subcon and his Vassal want to use the Power Of The Stars to protect Subcon. But King Wart and his gang known as the 8-Bits also sought the Power Of The Stars to use for their own purposes.
The following is from Ameba's Satellaview Library's BS Super Mario USA Power Challenge, and is part of the the plot of the game. 家臣「王様、星の力を使ってサブコンを守りましょう」 王様「よし、マリオ君たちにお願いしよう」 "Vassal: 'King, let's use the power of the stars to protect Subkon.'"............ "King: 'Okay, I'll ask Mario and the others.'"............ And しかし、星の力を使おうとしているのは、王様たちだけではありませんでした。あのマムーとその一味も力を悪用しようと企んでいます。 "However, the kings aren't the only ones trying to use the power of the stars. King Wart and his gang are also plotting to misuse the power."......... Basic Google Translation
So yeah, BS Super Mario USA is actually the first mention of the Power Of The Stars. Written by Eris the Lorekeeper