My question is about game development. Some game developers browse cgtrader and turbosquid looking for stock models. What I want to know is do the developers take the models without doing their own animations? Is it critical that my organic models are animated? Do I have to really include all those attack, dance and run animations? I think they would want a walk and run cycle. Maybe the die animation. But how are they able to take those animated models and put them in their own custom game design? I think they must be doing their own animations. With the exception they might use the walk loop.
Most of the times models are without animations. So it means that someone would have to create or generate all the equivalent animations needed.
Other times the skeleton / rig would not match at all the specifications of some developer so the skeleton is recreated from scratch and vertices are weight-painted again as wel for each individual character.
The best idea to roll with these sort of problems is to have a universal skeleton/rig that would fit all of the models in your game.
Once you have meshes from all characters you need, you would have to weight-paint all of them correctly so they can bend properly with the universal armature.
Essentially once you go to the game engine you would have a perfect combination of any [MESH+SKELETON+ANIMATION] working correctly.
A really good idea for a universal armature: Just ignore entirely the IK part, always use FK, however you can use IK as pilot or helper rigs. However you will eventually copy transformations from IK and bake them to FK.
About the universal armature: if you have werewolves and humans in your game you would have a super armature with all features of both of them ears+tail+etc. However for humans you would ignore irrelevant bones - just ignore the ears and tail. And same also for male/female characters.
To create animations: Really good ideas and workflows to take pilot animations and bake keyframes to the target bones. (Note that IK/FK thing mentioned earlier).
To export specifically animations/RIGS (but no MESHES at all - meshes exported only once separately)