>How can Mary be sinless (i get the catholic answer about her having the title of "full of grace" during her pregnancy with Jesus, but...) When she needed a savior?
Well, in Galatians 3:22 is says "But the scripture hath concluded all under sin, that the promise by faith of Jesus Christ might be given to them that believe."
Therefore, it is clear that all have sinned (like it says in Romans 3:23) and fallen short of the glory of God. The only way someone would try to tell you a person is sinless in a Biblical context would be if they were telling you someone is God. Obviously, according to the Bible everyone has sinned. This is a frequent theme. Jesus Christ, being God, is sinless. This is one way in which the Lord and Savior, Jesus, is different. As it says in Hebrews 7, He is "separate from sinners" among other attributes. He was born of a virgin, He alone is holy among all, and worthy and righteous, and His coming is a fulfillment of many ancient prophecies, such as Genesis 3:15 and many others—like it says in John 1:14, "And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth." It also says in 1 Timothy 3:16, "God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory." This last part refers to the fact that Jesus ascended into heaven after the Resurrection, after He died for all of our sins and transgressions on the cross and was in the grave until the third day when He rose again. Right now He continues to live due to the fact that He has resurrected and He won't die, as Jesus is quoted in Revelation as saying, "Fear not; I am the first and the last: I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death." All of these things are special to Christ Jesus.
Later, some came up with their own theories in which other people such as Mary are sinless, however they simply did not understand the Gospel and how it tells us that all have sinned. It is pretty clear to see that this is a satanically inspired lie, because it openly contradicts clear Scripture. It also takes advantage of people being confused between the difference of being "blameless" and being sinless. It says in Luke 1:6 that the parents of John the Baptist were blameless, but that doesn't mean they were completely sinless before God. The same goes for a lot of people. The fact that we are ALL sinful is shown by a statement in the book of Isaiah, where it says "But we are all as an unclean thing, and all our righteousnesses are as filthy rags;" In other words, what this means is from God's perspective, the best things we have done are still unholy and filthy. The things that we might consider righteous are still tainted with wickedness, as God sees all of our imperfections to an infallible accuracy. That's why we need Christ, the beloved and only begotten Son of God to intercede for us. He willingly came here in order to help us and provide a hope for our situation. What He asked is that we believe on Him. See John 5:24. "Verily, verily, I say unto you, He that heareth my word, and believeth on him that sent me, hath everlasting life, and shall not come into condemnation; but is passed from death unto life." In the epistle to the Colossians, another part of the New Testament, the apostle writes to the church: "You, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses; Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross." And our Savior did this because of how great of a person He is.
So it's important to understand how no one can save themselves from the wrath to come. In 1 Thessalonians 1:10 it says, "Jesus, which delivered us from the wrath to come." The only way to be delivered is through the Lord; Like it says throughout the Bible, Salvation is of the Lord. This would be circumvented if someone (other than Christ the Lord) was able to save themselves from condemnation, or was already without sin.
>Aren't we all sinners because of original sin, and doesn't that include Christ
Christ is not included in that because He is the only begotten Son of God. As quoted earlier, he is "separate from sinners" (Hebrews 7:26).