'Are you vegetarians?' would be «Ви вегетаріа́нці?».
(There's also a female form, «Ви вегетаріа́нка?». However, it's optional: you can use the male form веретаріа́нець when addressing women too.)
In English when asking questions, "You are a vegetarian? " had the same connotation as "Are you a vegetarian"
What do you say if you are a 'meatatarian'?(One who eats mostly meat.) I know people who are meatatarians.
Carnivore is the term for a meat-eater. Although, omnivores are what humans are usually, eating both meat and vegetables.
In American English we commonly say "are you vegetarian?". This asks what you are, not what group you belong to. It's conceivable there is nuanced meaning to the Ukrainian sentence which would make this not the correct translation, however I have reported it as an alternate translation.