This is not praying "with"; this is praying "to".
Obviously, Christ is not sufficient for Catholics. Seems He's not strong enough. Praying "to" Mary is done all the time thru the rosary. Prayers "to" other saints are made all the time as well.
Yes, a beautiful prayer asking the Mother of our Lord Christ Jesus - and therefore our Mother in the life of his Grace - to pray for us to her Son on our behalf. A very Scripturally based request I might add.
This is not praying "with"; this is praying "to".
At this point, it could become a semantic game, and really, on the street most Catholics would commonly say they were "praying to" Mary rather than "with". Not really a big deal, but there is a technical difference. When praying "with" the Angels and Saints, we are asking them - in and through our Lord Christ Jesus - for help in offering our prayers to God. When praying to God, and God alone, that is the Blessed Trinity, we never would word it like above. That is the "pray for us" formula, because that would be silly. Prayers to God ask Him directly for our needs, etc.
Obviously, Christ is not sufficient for Catholics.
Obvious to whom? Be considerate! Speak for yourself if Christ is not sufficient for you. It is dogma of the Catholic Faith that He is for super abundantly sufficient for everyone.
Seems He's not strong enough.
Why do you say this? I know no practicing Catholic, or other Christian for that matter, who believes this.
Praying "to" Mary is done all the time thru the rosary.
Case in point. A very beautiful meditative prayer asking Mary's help in contemplating the life of our Lord. Technically, this is a private devotion, as opposed to liturgical prayer, which is the public prayer of the Church. Scriptural to the core. From it's very heart in the meditation of the interior life of the believer, to the external vocal prayers used to facilitate the meditation. I recommend it to everybody, and know of Protestant Christians who use it as well.
Prayers "to" other saints are made all the time as well.
That's the great thing about being a Catholic. In the communion of Saints we recognize how God has given us each other as brothers and sisters in the Grace of Christ under his Fatherhood. Adopted sons and daughters is how St. Paul and St. John express it. Also, it is very Scriptural if you care to read Scripture in context. In an above post, I recommended a poster to expand and read his reference of 1 Timothy 2:5 for the full context. Here it is:
1 Timothy 2:1-7 (RSV)
"First of all, then, I urge that supplications, prayers, intercessions, and thanksgivings be made for all men, for kings and all who are in high positions, that we may lead a quiet and peaceable life, godly and respectful in every way. This is good, and it is acceptable in the sight of God our Savior, who desires all men to be saved and to come to the knowledge of the truth. For there is one God, and there is one mediator between God and men, the man Christ Jesus, who gave himself as a ransom for all, the testimony to which was borne at the proper time. For this I was appointed a preacher and apostle (I am telling the truth, I am not lying), a teacher of the Gentiles in faith and truth."
Note the parts that I bolded. How St. Paul urges Timothy to supplicate, pray, intercede, and give thanksgiving for all men. Also that he says it is good and acceptable to God our Saviour. This is one of many passages that we Catholics use to understand that God wants us to pray for one another. Asking for the prayers of Angels and Saints in heaven, who "have fought the good fight" and now contemplate God directly face to face, is all the more powerful and acceptable to God!