Moltres is going to be taking Articuno’s spot in just a few hours, so it’s time to cover the best ways to take this bird down. Moltres is both a Flying-type and a Fire-type, meaning that Rock-type attacks will be twice as effective. If you have access to a Golem or a Tyranitar with Stone Edge, now would be the best possible time to bring them into battle. They will slay the bird very quickly, especially if you have many of them on your team.
The second best option would have to be a strong water type. If you do have a high CP Gyrados, take that bad boy out and Hydro Pump the Legendary to death. Vaporeon is a more common, and almost as good, pick as Gyrados, as well as a Feraligatr if you have one. If you end up having a Latern, you can actually get the electric and water combo, however it isn’t 2x effective at any point.
Finally, you can break out some pure electric Pokemon. If you have some Jolteons, Raichus, Electabuzzes, and so forth. Just hammering this bird with as much water and electricity will definitely help take it down fast, but Rock is really your best bet. Good luck out there trainers! May Moltres soon be in your bag along with your other incredible catches!