Reflexive Pronouns is the forty-first (assuming read left to right) skill in the Welsh language tree. It contains two lessons, and the only words learned are the reflexive pronouns using hun, hunan, and hunain.
Welsh has reflexive verbs like English has, but they are handled differently:
Truly reflexive verbs have ym- in front of them. You do not need a pronoun for this.
If you use a reflexive pronoun with a regular verb, the rules are pretty abstract for the usage of the three pronouns. Use whichever is most comfortable. You will find that North Wales uses hunan for singular and hunain for plurals more often than not, however.
Duolingo Lesson: www.duolingo.com/skill/cy/Reflexive-Pronouns