Answer

In Jain tradition, the four kinds of devas are:

• Bhavanavasi
• Vyantara
• Jyotishka
• Vaimanika

They are usually classified by their realm and role, not by a formal “rarest” ranking. If you mean the one that is least commonly spoken of or most unusual, many people would point to Jyotishka devas, because they are connected with the sun, moon, planets, and stars.

Explanation

The usual order is:

• Bhavanavasi devas — dwelling in abodes or palaces
• Vyantara devas — roaming/intermediate devas
• Jyotishka devas — celestial body devas
• Vaimanika devas — heavenly devas in विमानों, and these are the highest among the four

So, if you are asking for the highest, it is Vaimanika. If you are asking for the most uncommon in everyday discussion, it is often taken as Jyotishka.

Spiritual Understanding

In Jain Dharma, becoming a deva is not considered the ultimate goal. A human birth is especially valuable because it gives the best opportunity for sādhana, self-discipline, and liberation. Devas enjoy many pleasures, but they do not have the same strong opportunity for spiritual progress as humans.

Takeaway

There is no fixed Jain rule that one of the four devas is the “rarest.” If you mean the most unusual among them, Jyotishka devas is the closest answer. If you mean the highest, then it is Vaimanika devas.