Lugia and Aritcuno are out in pokemon go now. They can be find in raids battle but be careful these beast are high level. So how to defeat a pokemon with such a high cp: team up with other players. Is the easies way to beat them. Even if you have a low cp pokemon you can get them as well.
It is also a rumor that zapdos and moltres will be joining soon as well.
Happy catching everyone