Can u tell what system should Pakistan procure which has capabilities like S400?
Definitely simply just S-400. I don't know the specific jobs and difference between hq19 hq26 and hq29. These projects even though quite old now, are constantly changing and details removed years ago even when documents and leaks were made. China doesn't want United States to update their offensive weapons and give them reason to fear. Our ballistic missile defense sounds like doesn't exist but behind curtain been working on different ideas since 1970s at least 1980s I'm sure. The older Chinese managers were always wanting to get to top even in the poorest conditions. Mao looked at nuclear bomb and said no matter how many people starve, we must develop it. Now the technology allows for something similar to THAAD and SM-3 and A-235.
If Pakistan need the best air defense system against fighters, missiles, and short ballistic missiles, then S-400 is probably can deal with everything. Depends on what Pakistan itself realizes is best and what the system will be defending against. HQ-9 may be good enough and possibly much more affordable than S-400 and can deliver quickly. I don't think China will sell 19, 26, and 29 because even they still keep mouth shut about these until now. Some are just developed from HQ-9 and include more boost phase to get higher altitude and speed. Rest are based on anti satellite technology and similar things for near space in outside atmosphere targets.
S-400 I don't think Russia will sell to Pakistan because there will be so much pressure from India. Best defense is attack. So maybe some HQ-16 and HQ-9 systems can do the job for much cheaper price and rest of funding can be spend on better fighter jet and weapons. Air defense strategy of Pakistan looks more like keeping Indian airforce out and maybe at most attacking Indian airbase and weapons depot. We know HQ-9 is very good at least ten years ago. It beat every target in Turkish testing and Patriot S-300 and Aster could not match total performance. This was just B version or maybe even dumb down earlier version just for export. If both Pakistan and China consider the threat from India is very intense, I think no doubt Pakistan can easily get many HQ-9B/C to protect important sites with HQ-16 to cover and HQ-17 which is Tor-M1 copy. Chinese say we improved the missile and there is quite a lot of difference to the rocket from just pictures. Truck and design is same. Anyway these can overlap in layers of defending something.