Unless the PRC or Iran helped Pakistan any war between these two would be catastrophic for Pakistan.
India could could absorb loses equal to the entire population of Pakistan
“India could could absorb loses equal to the entire population of Pakistan”
The political impact of such loses needs to be evaluated. I suspect that unless a war went spectacularly well, the current government would fall. Also, it is unlikely that China would sit on the sidelines, especially when they want to test their new stealth technology. China could seriously dent India’s ability to defend itself, thus allowing Pakistan to launch a nuclear strike. With China absorbed in that arena other Pacific players might take it upon themselves to move China out of their particular conflict regions. So, with a simple strike of an Indian match that entire part of the globe could go up in flames. This is how, in principle, World War I started. Lawyers call it proximate causation.