Technically you can animate rigged characters in Unity but it’s a huge pain and far more time extensive than necessary. For most animations I’d recommend using an external program like Blender, especially for rigged characters. The only exception would be for very simple “looking” or “grabbing” motions, for that you could use IK in Unity. An example of this would be having your player look in a specific direction, or if you wanted to reach out and grab something, again you could use IK. Those are more procedural types of movements and are best used in the game engine as you can’t really animate those. Here are some rigging and animation courses that can help you out: https://cgcookie.com/lesson/armature-properties and https://cgcookie.com/course/fundamentals-of-rigged-animations
