"Go to school yourselves."
Translation:Mergeți voi înșivă la școală.
The use of pronouns is or is not necessary depending on the context. The emphatic pronoun (pronumele de întărire) always accompanies the noun or pronoun that it emphasizes.
(Tu) citești poezia. = You read the poem. --- the pronoun (tu) is optional
(Tu însuți) citești poezia. = You read the poem yourself. --- if the emphatic pronoun is present (însuți), the pronoun it emphasizes (tu) has to be present too
No, Romanian uses Vocative case for imperatives. Duo does not bother you with vocative for pronouns, because it is mostly like nominative, and it is always a big source of arguments between linguists. Romanian language evolved at the confluence between European, Oriental (Tartar/Mongol, Turkish), Greek and Slavic languages, and it has a very colored vocative (especially for invectives :)) which is not always accepted, in spite of the fact that it is in a quite common use (for example, you cannot use vocatives in a Scrabble game).
Here the ”pronoun” is ”voi înșivă”, which is not separable. Take it like a locution or idiom. A ”mot a mot” translation would be ”you by yourself”.