“I’m not sure how the Catholics (or the Nicene majority, for that matter) resolve the dispute about Jesus praying to God in the Garden of Gethsemane or later on the cross. Is he praying to himself?”
I’ve witnessed this argument put forth by those in the mormon cult many, many times. They consider it convincing in some way. It is not.
I’ve come to understand this is a persuasive argument to mormons because it rests on the foundation of a misunderstanding of the nature of God. Mormon teaching perverts the image of God by making Him into a mere created being. It perverts the nature of God by making god into less than god. It multiplies gods instead of rightly dividing the Scriptures to understand the true image and nature of God. All of these theological errors lead to statements like the one quoted above.
In the end, Satan’s Fashion Show continues to bring back heresies from the past, time and time again. Mormonism has plenty. Jehovah’s Witnesses have plenty. They often overlap as to their favorite falsehoods. Both cults are American Made.
Bonus: Mormonism has 4 Earth Gods: Mormon God the Father, who was created and later became a mormonic god. Mormon Jesus, who started life as a created spirit-being (just like Satan), The mormon Holy Ghost, who was created, but did not get a body because he did something naughty and finally Mormon Heavenly Mother, who was a created spirit being, who got a body and is now eternally sealed to Mormon God the Father. They breed in the heavens. She is eternally pregnant and pops out spirit children to populate the earth.
There may be more than one Mormon Heavenly Mother... the mormonic verses and cult teach there is eternal polygamy.
But I fail to see how that makes them any more sound doctrinally than the defeated Arians. Notwithstanding that I find a few things wrong with Arian branch theology as well.
Nor do I see how taking literally repeated scriptural references to Jesus being the only begotten son of God somehow makes him less than God.
Meanwhile, I notice both of your identified cult sects (Mormons and JWs) which you so heartily condemn are still very much standing their ground against homosexual marriage whereas the Nicene mainline protestant sects have, for the most part, surrendered to the gay mafia. Said surrender really makes them little different than the "cafeteria Catholics" like Nancy Pelosi or Joe Biden.