Songs that has not been approved or sung by bonafide devotees are not allowed.

In Krishna consciousness movement any song that has not been approved or sung by bona fide devotees is not allowed. Any cinema songs are not allowed to be sung in the temple. The devotees generally sing two songs. One is jai sri-Krishna-caitanya prabhu nityananda sriadvaita gadadhara srivasadi-gaura-bhakta-vrnda. This is bona fide. It is always mentioned in the Caitanya caritamrta, and it is accepted by the acaryas. The other, of course, is the maha-mantra–Hare Krishna, Hare
Krishna, Krishna Krishna, Hare Hare. Hare Rama, Hare Rama, Rama Rama, Hare Hare. Songs of Narottama dasa Thakura, Bhaktivinoda Thakura and Locana dasa Thakura are also allowed, but these two songs–“sri-Krishna-caitanya” and the Hare Krishna maha-mantra–are sufficient to please the Supreme Personality of Godhead.

Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Eighth Canto, Chapter 5 – Text 25