Can Gaura Nitai be offered Tulasi leaves, or because They are in the mood of a devotee we dont?
Śrī Gaura-Nitāi are considered Viṣṇu-tattva in the Gauḍīya Vaiṣṇava tradition.
Śrī Caitanya Mahāprabhu (Gaura) is Kṛṣṇa Himself, appearing as a devotee to teach and distribute prema-bhakti, especially through the chanting of the holy name.
Śrī Nityānanda Prabhu (Nitāi) is the original Balarāma, who is also Viṣṇu-tattva and the first expansion of Kṛṣṇa.
Therefore, Gaura-Nitāi are not ordinary living beings (jīva-tattva) or demigods; They are Viṣṇu-tattva and are worshipped accordingly.
Śrī Caitanya Mahāprabhu (Gaura) is Kṛṣṇa Himself, appearing as a devotee to teach and distribute prema-bhakti, especially through the chanting of the holy name.
Śrī Nityānanda Prabhu (Nitāi) is the original Balarāma, who is also Viṣṇu-tattva and the first expansion of Kṛṣṇa.
Therefore, Gaura-Nitāi are not ordinary living beings (jīva-tattva) or demigods; They are Viṣṇu-tattva and are worshipped accordingly.
So Gaura-Nitāi can and should be offered Tulasī leaves. A useful principle for Deity worship is that Tulasī is offered to Viṣṇu-tattva forms of the Lord. So in home worship, it is appropriate to offer Tulasī to Gaura-Nitāi, as well as to Rādhā-Kṛṣṇa and other Viṣṇu-tattva Deities.
This is my understanding. Hare Krsna
Considering Gauranga appeared as a Golden Avatara representing Radha Krishna it is Vishnu Ttava. Also, Nitai is a none other than Lord Balaram.
I think you have a valid question. As a devotee, the mood of Lord Chaitanya is to serve Tulasi and not to get served by her. In fact, sometimes I even feel that when it come to offering Tulasi on feet, should we not offer Tulasi only to Vishnu deity - saying so because Tulasi is associated with Vishnu (and Shaligram)...so the relationship of Tulasi with other Vishnu forms is not there. By associating Tulasi with other forms is it not like pairing Sitaji with Krishna, Radha with Narsimha, Laskhmi wit Ram, etc?