Rakshasa gana carries the heaviest name of the three and the most misreading. The word names a class of beings in Indian mythology, and translations reaching for demonic or fierce import a moral verdict that the technical use does not carry. In the ashtakuta reckoning the gana is a category in a compatibility scheme, not a judgement on a person, and the classical literature applies it as such.
Nine nakshatras are assigned to it: Krittika, Ashlesha, Magha, Chitra, Vishakha, Jyeshtha, Mula, Dhanishtha and Shatabhisha. That list includes several of the mansions the texts treat as difficult on other grounds as well, Ashlesha, Jyeshtha and Mula among them, which is one reason the category and the reputation reinforce each other in popular accounts more than the technical scheme warrants.
The use is gana kuta, one of eight factors in the thirty six point ashtakuta method used across much of North Indian jyotisha to weigh a proposed marriage. It is worth six points. A pairing of a rakshasa nakshatra with a deva one is the combination the method scores lowest, which is why this gana attracts the most attention of the three, and why practitioners are also the ones most careful to say that one factor out of eight does not settle anything and that the rest of both charts is examined.
This is current practice in India and in the diaspora, described here rather than prescribed. Chart work belongs with a jyotishi.