No council has ever claimed to contain all the truth but what they taught is without error. They do so with the same authority as the Council of Jerusalem that was recorded in Acts.
V2 changed a lot that sedevacantists and traditionalists reject. So who's correct?
Vatican II did not change any doctrines of the Church.
And what about the schism between the Orthodox and the Roman rite? Each claim to be the church that Christ started in its purest form with the other being in schism.
Who's right and why? What truth standard is used for making that determination?
The historical record shows that the undivided church acknowledged the role of the pope. It is they that have departed from what was the accepted teaching of the Church.
Baloney. Try that on someone who doesn't know anything about Catholicism.
The whole issue of whether someone can be saved outside of the Catholic church is probably the best known one.
In that case you have a link to that info right?
Claiming something like that needs proof.
I will forgo asking for proof from the Bible because the Word of God has a different take on that.