Teo“2. He is
the very tallest student in the class.
5. She is the very most beautiful girl in the class.
#2 is correct. Is #5 also acceptable?
”
2 is redundant - if he's the tallest, he's the tallest. You can't be "more tallest" or "very tallest." However, even so, "very tallest" can be used colloquially to emphasize just how tall he is.
5 is not correct. If she's the most beautiful, she's the most beautiful. You can't use "very" and even colloquially, that won't work.