1. Literally so easy if you know what story he's from. He's the main Bad guy in the story...

2. A diety of darkness who tried overthrowing Arceus, only to be stopped by 10 warriors, appointed by Acreus himself to protect the light. He was defeated when Acreus intervenes with the battle.

3. He was willing to let his own son die, seeing how his son was one of the 10 chosen ones.

Extra: How many of the 10 died in the fight against this character?