So Bishops in union with the Pope in a General Council and/or Bishops approved by a Pope in a General Council would not be infallible in any circumstance, correct?
That's right, bishops cannot speak ex cathedra, only the pope can speak ex cathedra. The bishops can petition the pope to define a dogma, but per V1, even dispersed throughout the world or all together since the the time of the Apostles, the bishops do not have the power to define any dogma, none whatsoever, not ever, never have and never will. All they can do is the same as the rest of us can do - ask the pope to do it.
Pope Pius IX Ineffabilis Deus
: "Accordingly, from ancient times the bishops of the Church, ecclesiastics, religious orders, and even emperors and kings, have earnestly petitioned this Apostolic See to define a dogma of the Catholic Faith the Immaculate Conception of the most holy Mother of God."
The bishops petitioned the pope to "define a dogma"
because they cannot do it, note they asked him to define a dogma, not "speak authoritatively to the whole world" as you alluded to in past posts and continue doing.
Here is the wording for the actual defined dogma of the Immaculate Conception from the same link:The Definition
Wherefore, in humility and fasting, we unceasingly offered our private prayers as well as the public prayers of the Church to God the Father through his Son, that he would deign to direct and strengthen our mind by the power of the Holy Spirit. In like manner did we implore the help of the entire heavenly host as we ardently invoked the Paraclete. Accordingly, by the inspiration of the Holy Spirit, for the honor of the Holy and undivided Trinity, for the glory and adornment of the Virgin Mother of God, for the exaltation of the Catholic Faith, and for the furtherance of the Catholic religion, by the authority of Jesus Christ our Lord, of the Blessed Apostles Peter and Paul, and by our own:
“We declare, pronounce, and define that the doctrine which holds that the most Blessed Virgin Mary, in the first instance of her conception, by a singular grace and privilege granted by Almighty God, in view of the merits of Jesus Christ, the Savior of the human race, was preserved free from all stain of original sin, is a doctrine revealed by God and therefore to be believed firmly and constantly by all the faithful.”
Hence, if anyone shall dare — which God forbid! — to think otherwise than as has been defined by us, let him know and understand that he is condemned by his own judgment; that he has suffered shipwreck in the faith; that he has separated from the unity of the Church; and that, furthermore, by his own action he incurs the penalties established by law if he should are to express in words or writing or by any other outward means the errors he think in his heart.