Related על מגילה 2:4

One who read [the Megillah] at night did not fulfill his obligation. Said Rabbi Yosei, it so happened with Rabbi Yochanan ben Nuri that he read [the Megillah] in Sepphoris at night. They said to him, a time of danger (i.e., of persecution) is not a proof. One who recited [the Megillah] by memory did not fulfill his obligation. Said Rabbi Shimon ben Elazar, it so happened with Rabbi Meir that he went to Asia Minor to pass the year and he did not find a Megillah there written in Hebrew. So he wrote it from memory and he went back and read from it. One who read [the Megillah], whether standing, whether sitting, whether lying down, whether he appointed a[n Aramaic] translator, whether he made a blessing before [reading] it, or whether he made a blessing afterwards, [or whether he made a blessing] afterwards and did not make a blessing beforehand, or whether he did not make a blessing either beforehand or afterwards -- he has fulfilled [his obligation]. Said Rabbi Shimon, it so happened with Rabbi Meir that he read [the Megillah] in the synagogue in Tibin sitting down, and the congregation was sitting down, and as soon as he finished part of it, he gave it to someone else and he (i.e., the other person) blessed over it.

Everyone is liable in reading the Megillah -- Kohanim, Levites, and Israelites, and freed slaves, disqualified [Kohanim], Netinim (i.e., descendants of Gibeonites), and mamzerim, eunuchs, those born sexually impotent, one wounded with crushed or severed testicles (=פצוע דכא וכרות שפכה, see Deut. 23:2), all of them are liable, and can cause others to fulfill their obligations. A hermaphrodite fulfills the obligations of his (or her) gender but not of those that are not of his (or her) gender. One who is half slave and half freedman does not cause those that are of his gender or not of his gender to fulfill their obligation. Women and slaves and minors are exempt and they do not cause others to fulfill their obligation. Said Rabbi Yehuda, when I was a child I read [the Megillah] in front of Rabbi Tarfon in Lod and he praised me. Said Rebbi, when I was a child I read [the Megillah] in front of Rabbi Yehuda in Usha, and there were elders there, and none of them said a word. They said to him, one cannot bring a proof from one (i.e., such as Rabbi Yehuda), who permitted that very thing to be done. [Nevertheless,] from that time and onward, they became accustomed to permit minors to read [the Megillah] in public.