It depends on the season. Season one had Ash Ketchum, Misty, and Brock as the three main characters, along with Pikachu and the other pokemon, as well as Ash's rival, Gary, and Team Rocket, which consisted of Jesse, James, and Meowth. However, later seasons have May, her little brother, Dawn, and other rivals and gym leaders.
Chat with our AI personalities
they are dawn and lucas
By main characters, I think you mean the player characters. If so, yes, they have names. The boy is named Hilbert, and the girl is named Hilda. Their Japanese names are similar as well. The boy's is Touya, and the girl's is Touko.
YOU CAN'T, you have to get the game in Tokyo/Japan in order to make the words on pokemon heartgold be japaneze. If you get it in a English state, it will be English!
check your national pokedex check serebii.net :)
The longer you play the games, the more you'll remember all the names. Few people could sit down and name every Pokemon from memory alone, but many players could probably name them all if pictures were provided.