CAN A NON AALIM PERFORM A NIKAH

Any Sunni can perform a Nikaah. However, it is mustahab (desirable) for the one who performs the Nikaah to know the Islamic rulings related to Nikaah and he should be a righteous and practicing Muslim and this just as it is in Durr e Mukhtaar:

These are the words of Durr e Mukhtaar that, it is Mustahab to announce the Nikaah, to have the Khutbah of the Nikaah in the Masjid before it, for it to be on a Friday and for the person who performs the Nikaah to be one who is aware of the Islamic issues (rulings) related to Nikaah and should be a righteous Muslim. (Durr e Mukhtaar, Chapter of Nikaah, page number 187 / Dar Al-Kutub Al-Ilmiyah) Huzoor Ala Hazrat Alaihir Rahma says:

Ar-Rushd (Awareness / Proper Guidance) includes both Ilm (knowledge) and Amal (action). Furthermore, Huzoor Ala Hazrat Alaihir Rahma writes in Fataawa Razviyyah Shareef that, the person who is going to perform the Nikaah should be religious, pious and should be aware of the Islamic issues (rulings) related to Nikaah, because an ignorant person was expected to make a mistake unknowingly (due to ignorance) during the performing of Nikaah. A Faasiq (transgressor) is one who cannot be trusted, because when he himself does not care about Halaal and Haraam, then what kind of caution can be expected from him for others. (Fataawa Razviyyah Shareef New edition Volume 11 page number 186)

The Summary of all the above is that, Nikaah can be performed by any such Sunni Sahihul Aqeedah who is well aware of the Islamic issues (Rulings) related to Nikaah and he is one who is a practicing Muslim.