I think saudia and iran should also be invited. They are a party in this conflict. Let them discuss how they want to destroy Pakistan! I want to listen to them because it's very necessary for us to know what kind of intentions they have!
I am almost certain that Iran has nothing to do with the Shia clerics under discussion here.
Although I did not conduct any further research into their affiliations, they pretty much sound like followers or sympathizers of the so-called "Shirazi clan", a marginal current of Shia clerics known for their questionable positions. To name a few: they are sectarianist and insist on cursing certain figures revered by Sunni Muslims - whereas Iran's Supreme Leader seyyed 'Ali Khamenei issued a fatwa prohibiting just that; they reject the concept of Islamic Shia-Sunni unity promoted by Imam Khomeini and Imam Khamenei; and they advocate the practice of tatbir or ghame' zani (use of blades to self-inflict wounds) during 'Ashura processions, again contrary to fatwas issued by Imam Khomeini and Supreme Leader Khamenei, who deem it impermissible. On one of their many satellite TV channels, I once heard a presenter advocate that the faithful allow horses to walk over their bodies at Karbala... Way to project a negative image of Shia Islam to the outside world!
See:
english.khamenei.ir
english.khamenei.ir
Now the most interesting part in all this is that the "Shirazi clan" and associated clerics are staunch opponents of the Islamic Republic of Iran and its leadership. Some of them, like Kuwaiti sheikh Yaser al-Habib, a resident of the UK, have directed vile insults at Hassan Nasrallah, the Secretary General of Lebanon's Hezbollah, for actually not being sectarianist and for considering Sunnis as his brothers in Islam. Another one, the Afghan sheikh Allahyari, who resides in the US, regularly uses hair-raising offensive language against Supreme Leader Khamenei.
These examples readily highlight another characteristic of these people: they are based to a large extent in the UK and the US. According to Iranian sources, they are on the payroll of western intelligence services, who use them to achieve two simultaneous goals: one, feed Shia-Sunni strife from out of the Shia camp - seeing how Iran and its leadership are working against this divide, the enemy needed to manufacture a properly sectarianist, anti-Sunni current within the Shia community; and two, try and engineer an anti-Iran movement amongst Shia Muslims, i.e. turn fervent religious Shias against the Islamic Republic of Iran and the Islamic Revolution. Which is why in Iran, they coined the term "British turbans" ("'Ammāmehāye Englisi") to designate these individuals .
Thus, it comes as no surprise that in comparison to their actual real-life relevance, these "Shirazis" and like-minded groups have disproportionate financial means at their disposal, and an abnormally elevated number of satellite TV networks (more than 10 or so), an unrealistically large presence on the internet etc. Unfortunately, they have gained a certain foothold in Pakistan as well. Obviously, certain imperialist - read: western, zionist - entities not interested in peaceful relations between Shia and Sunni Muslims, the same ones which also prop up takfiri extremists on the Sunni side, are behind this anti-Iran and anti-Sunni brand of Shia clerics. Years ago, Iran shut down the local offices of their TV channels and arrested some of their ringleaders.
Once again, I cannot draw any conclusions about the Shia alims mentioned in the OP, for I never heard of them. All I'm saying is that they seem to fit the above described profile. And if on the contrary, they really are Iran-friendly ones, then they completely misunderstood Supreme Leader Khamenei's guidelines, or else they would not have proposed such a silly challenge. This much is for sure.