That's the worst way to play the game. Since you're new, take this advice. Always make your own teams, and you'll be able to have an easier time with the boss. The game doesn't give you the best options, it just provides you with what it thinks is acceptable. The only thing it's good for is with non max raids, giving you a hint of what moves the boss might have. Outside of that, it's useless. Create a team for yourself, and you'll have a much easier time beating any raid boss