A 2318 CP Dragonite defends a gym from a 1456 CP Charizard in a video (2:50 - 3:30). Here are the details of those Pokemon, the video, and the description.
Instead of Flamethrower, Dragon Claw is recommended as a charge move for Charizard to beat Dragonite. The move is super effective against dragon-type Pokemon.
To see the details of Dragonite, such as the stats and the evolution chart, tap the name of the Pokemon.
Video
1.
The Dragonite's fast move, Steel Wing, is not very effective against the fire-type Pokemon, but the move damages the Charizard much due to the Dragonite's higher CP.
The Charizard's fast move, Wing Attack, cannot decrease the HP of the Dragonite since the Charizard has very lower CP.
2.
Once the energy bar is filled, the Charizard uses Flamothrowe, but the special attack is not very effective against the Dragonite.
3.
As a counterattack, the Dragonite shoots Hyper Beam, a very powerful normal-type charge move. The Charizard fails to dodge the special move and falls down.