Naattai: This is an offshoot of Chala Naattai, which means it takes some notes of Chala Nattai, as a result of which it sounds similar to Chala Nattai in some prayogams... As with most janya ragas, there are 2 views regarding the scale of this raga.
One being, Sa Ri3 Ga3 Ma1 Pa Dha3 Ni3 Sa
Av: Sa Ni3 Pa Ma1 Ri3 Ga3 Ma1 Ri3 Sa
and the other:
Sa Ga3 Ma1 Pa Ni3 Sa -Sa Ni3 Pa Ma1 Ri3 Ga3 Ma1 Ri3 Sa
"Ri3 Ga3 Ma1 Ri3 Sa" is the most important prayogam for Naattai.. This and the absence of Dha3 in the avarohanam (descending) scale should be enough to distinguish Naattai from Chala Naattai. Maha Ganapathim is a popular song in this raga. source
One of my favorite songs.