Is it okay to stand behind an Imam (in Salah) who has shaved his beard?
If there is anyone else whose appearance (i.e. dress, beard etc.) is more in accordance to the Sunna, and is able to recite the least amount of Quran that is necessary for the validity of Salah, then it is not permissible to adopt an Imam who has shaved his beard, and it is also Makrooh (disliked) to perform Salah behind him. (Giving the Iqamat in such congregational Salah is also not devoid of dislike.)
And Allah knows best.