Who may argue against a Pope - and how....

Only Apostolic Tradition & binding Magisterial Papal Doctrinal & Moral Precedents can be used to argue against the present Pope [while acknowledging that no Pope may be bound in administration or discipline by his predecessors]
ONLY a very specific definitive formal structure to a decree ie appeal to apostolic tradition and longstanding ordinary sensus fidelium and a solemn invocation of Petrine authority - can any Papal [non-disciplinary] pronouncement be declared as infallible.
eg Leo XIII in Apostolicae Curae or St John Paul II used this form when denying the possibility of women priests
[ie the Church CANNOT EVER reconsider the validity of Anglican orders or permit women priests - the issue is over - a Pope - irrespective of their personal wishes is already absolutely proscribed from even raising the issue - Rome has already spoken and eternally spoken and every Pope is bound to uphold and defend that living voice from the past]
Therefore in order to argue against a Pope we need to use the words of a papal predecessor - eg where their ecumenism defies Mortalium Animos, where their Notions of Religious Liberty, Conscience and freedom of self-expression and self-determination contravene Libertas, where their doctrinal aberrations are contrary to Pascendi etc etc etc.
So when it comes to this Present Pope we need the words of Another Pope to tell His Holiness "where to get off" and to "get his act together"
Maybe we should start with Pius VI in Auctorem Fidei in response to Pope Francis's notorious technique of fluctuating peak and trough ambiguity in saying something outrageously Contra-Catholic or anti-tradition at one time while maybe reiterating something ostensibly stridently conservative a few sentences or perhaps a few days later? Pope Pius VI tells us....
“Moreover, if all this is sinful, it cannot be excused in the way that one sees it being done, under
the erroneous pretext that the seemingly shocking affirmations in one
place are further developed along orthodox lines in other places, and even in yet other places corrected; as if allowing for the possibility of either affirming or denying the statement, or of leaving it up the personal inclinations of the individual – such has always been the fraudulent and daring method used by innovators to establish error. It allows for both the possibility of promoting error and of excusing it.
“It is as if the innovators pretended that they always intended to
present the alternative passages, especially to those of simple faith
who eventually come to know only some part of the conclusions of such
discussions which are published in the common language for everyone’s
use. Or again, as if the same faithful had the ability on examining such
documents to judge such matters for themselves without getting confused
and avoiding all risk of error. It is a most reprehensible technique for the insinuation of doctrinal
errors and one condemned long ago by our predecessor Saint Celestine who
found it used in the writings of Nestorius, Bishop of Constantinople,
and which he exposed in order to condemn it with the greatest possible
severity. Once these texts were examined carefully, the impostor was
exposed and confounded, for he expressed himself in a plethora of words,
mixing true things with others that were obscure; mixing
at times one with the other in such a way that he was also able to
confess those things which were denied while at the same time possessing
a basis for denying those very sentences which he confessed.
“In order to expose such snares, something which becomes
necessary with a certain frequency in every century, no other method is
required than the following:
WHENEVER IT BECOMES NECESSARY TO EXPOSE STATEMENTS WHICH DISGUISE SOME SUSPECTED ERROR OR DANGER UNDER THE VEIL OF AMBIGUITY, ONE MUST DENOUNCE THE PERVERSE MEANING UNDER WHICH THE ERROR OPPOSED TO CATHOLIC TRUTH IS CAMOUFLAGED.”
...Kasper & Synod? who am I to judge? the Jews don't need Christ? Lutherans wishing communion can 'go to the Lord"? Permanent barriers prevent the return of the Orthodox to the Catholic fold? Condoms are better than abortions? I don't believe in a Catholic God? There are no souls in hell - anyone sent there is annihilated? etc etc etc....