Zidane- "ore", in Katakana, sorta a slang word.
Garnet- "watashi" or "watakushi", in hiragana, a rather polite form.
Steiner- "jibun" a term used by soldiers.
Freya- "watashi" in kanji.
Quina- "watashi" in katakana.
Amarant- "ore" in kanji.
Eiko- "Eiko" in a childlike way.
Vivi- "boku" in Katakana, a somewhat polite form.
In the final scene, "boku" is used by the narrator. Seeing that Vivi is the only character that uses this form, it is easy for the Japanese text to show that it is indeed Vivi talking, saying a final farewell to his friends.