We can find this answer in Rambadan Rai and others vs. Paltan Paswan and other,(AIR 1977 Pat 1), the Patana High Court held that, If a minor is a party to the suit and is not represented properly in the suit. Then the ex parte decree, which is passed against a minor, is not bound due to not representing in a proper manner as per the provision of the law. There is no legal validity of such decree, which is passed against a minor lacking appropriate representation in the suit. So the minor does not require to apply to set aside such decree under Order 9, Rule 13 of the Civil Procedure Code 1908. Such decree is called nullity in the eye of law that is not binding a minor. Also, there is no requirement to set aside such a type of decree.
Let’s see some other observations of the various courts regarding that.
In the case of Ramchandra Arya v. Man Singh (AIR 1968 SC 954), the Supreme Court held that whether a decree passed against a lunatic without appointing a guardian and execution of that decree were sold his properties. Then the Supreme court observed that a decree passed against a lunatic is a nullity, and the sale made via execution of that decree is void ab initio.
In the case of Kathaswami Chettiar vs. Ramachandran A.I.R. (21) 1934 Mad. 428, the Madras High Court held that A guardian of the minor defendant by defaulting wrong allows the claim for decreed to ex parte against a minor, which creates sufficient reason for non-appearance of the minor in the suit per Order 9 Rule 13 of the Civil Procedure Code 1908.
After discussing the above judgments, we can say that Ex parte decree against the minor was not correctly represented the guardian in the suit. Such decree can be considered a nullity, and there is no application required to set it aside.