When I was a young boy (early 90's) I watched an animated movie, possibly an anime, and it always stuck in my head. Problem is I can't remember the title. I will try to describe it so can you guys/gals please help me.
"One day the protagonist's schoolfriends go on a school trip to the electropower dam that his father designed but he stays behind because he can't confront it. Mean time on another planet/dimension evil guys unleash a mechanical beast upon the dam. While the beast is destroying the buildings, endangering the people and students, the protagonist senses this and rushes to rescue his friends. Because he's actually an alien (royal family) from another planet that the attacking aliens destroyed, he has the ability to transform/pilot into a giant robot and uses this power to fight the evil beast. He starts to lose the fight against the beast but his friends get contacted by another entity and are granted flying machines/mechas to support their friend. They defeat the beast by redirecting solar beams to power up the protagonist's mecha."
Other notable facts are. - The protagonist is the leader of the football team - the other entity I mention is a pure white man on a pure white pegasus, I think he wields a lance of light. - the crest of the royal family he descends from is a burning sun. - the evil aliens hold the protagonist's mother (the queen) captive on their planet. - when the protagonist transforms we see shots of his muscles growing. - the protagonist's mecha can combine with the machines of his friends.