Anime about boy transforming into/summoning red robot using red crystal

Question

I'm from Poland, and I remember that I saw an old anime on television about a boy who found some sort of red crystal that allowed him to transform into/summon red robot. He was attacked by people with similar crystals in different colors, who also could transform into/summon robots. I think they could've used them kind of like stands in JoJo, but I'm not sure. I think that in one episode he was attacked/used his crystal in his room. Also I think I remember him standing on a roof of his school campus with the robot floating near him.

For some unknown reason I associate it with Power Rangers. At this point I'm not even sure if this is real anime, or if I am just imagining things.

Answer 1

Promoting an answer from the comments which was confirmed by the querent as 90% likely to be correct, Power Stone.

The story takes place during the 19th century; Edward Falcon (Édouard Fokker) finds himself on a quest to find the magical power stones and his father, in order to save the world.

Opening Credits

You can see Edward transform into his red armor at about the 38 second mark. For reference, a video showing all of the Power Stone transformations:

Answer 2

Yo, I found it HURRAY!!!! It's called Bakugan. We got it right about the protagonist, Dan Kuso.

In this anime adventure series, a bunch of more-than-ordinary playing cards drop from the sky, landing all over Earth. A group of friends who pick up the cards -- Dan, Bruno, Marucho, Julie, Shun, and Alice -- team up to become the Bakugan Battle Brawlers. The Battle Brawlers must assist in the battle between good and evil in a parallel universe. As they learn more about the cards, they discover more about the power struggle in the alternate universe of New Vestroia, and do their utmost to help the Bakugan there win the day.

_{Tubi TV}