Enemies in Shadow of War are listed on this page.
In addition to the standard orc fodder that you'll be hacking apart, the game will feature a variety of other enemies to tangle with that will present different challenges. The bestiary is going to be fleshed out with even more variety than the first game and some of these will also be rideable beasts of destruction. In particular you will be able to commander siege beast from the opposition and use them to demolish your foes.
Drakes will be present in both scripted and random encounters and they don't discriminate, wrecking havoc on friend and foe alike. But they can turned to your side, you'll be able to mount and ride a drake into combat. In order to do so you will have to break it in the wild, by bringing it down to the ground via ranged combat. Once it's downed, you will have to move in and use melee to subdue it. Once you do, you'll mount it and it will be on your side for good, even if you hop off. Later on you'll be able to use an ability that lets you teleport to mount them from a distance, making this a much easier process. Your summon mount ability can also be upgraded to summon one at will. Once you're riding a drake, you can also eat orcs to regain health as you devastate the landscape. Eventually you will be able to charge an explosive fireball for even more destruction.