ABOUT:
■ These are plural markers for personal pronouns or proper nouns for people.
HOW to use:
■ たち: Useful in most any situation. Used with all pronouns except 彼 (he). Used with nouns and names of people.
→ 私たち
→ あなたたち
→ 彼女たち they (female) [彼
he takes ら in the plural: 彼ら they]
→ 青木さんたち the Aokis
→ 生徒たち the students
■ がた: This is an honorific plural marker which is mostly used with あなた and a few respectful positions and professions (mother, professor, teacher).
→ あなたがた you (plural; respectful)
→ 先生がた the teachers (respectful)
■ ら: This is the least formal plural marker. It can be used with humble and non-formal pronouns.
→ 僕ら we; us [僕 has a humble feel. You can use this with わたし but you wouldn't use it with the honorific わたくし]
→ 君ら you (plural) [君 is also humble. ら can be used withお前 but not あなた. This is used for one's peers or those younger than you, but not for those older or higher up socially.]
→ 彼ら they (male or mixed)
→ 彼女ら they (female)
→ お前ら you guys (a little rude/familiar)