"each student" or "each country" is said "それぞれ" in Japanese. ・Each student started to talk. 【生徒はそれぞれ話し始めた。】 ・Each country have to cooperate together. 【それぞれの国は、互いに協力しなくてはいけない】 "おのおの" and "各自" is more formal than "それぞれ". If you use this word in ordinary conversation, I think you had better to use "それぞれ" I hope it will be helpful to you !

In Japanese, "each" can be translated as  "それぞれ", " 各自(かくじ)", and "おのおの". eg. each student それぞれの生徒       each country それぞれの国 (But the accurate translation of "each"will change according to contexts. Sometimes it is even omitted in translation,like the second example below.)       Each country signed the treaty.          それぞれの国は条約に調印した。／各国は条約に調印した。       Each student supposed to have lunch at their home.        生徒はおのおの／生徒は各自、自宅で昼食をとることになっています。 ／生徒は自宅で昼食をとることになっています。