I want to explain why I virtually never discuss Japan's or South Korea's military. Technologically, Japan and South Korea have more powerful militaries than India.
However, India has an important advantage over Japan and South Korea. India has strategic depth. It is my belief that once the PLA starts ripping into South Korea, the war will be over in a couple of weeks. However, India is one million square miles and there is a lot of Indians to chase down. It will take forever.
In my opinion, India is a much more formidable military opponent for China. It will be extremely difficult to subdue India. The idea of occupying all those overpopulated Indian cities is a nightmare. However, occupying South Korea is a minor logistics issue. Once you capture Seoul, South Korea has fallen.