Moses and Elijah is a good guess.

Some alternatively say Enoch and Elijah. Depending on which Bible Canon you accept, you have Sirach (Ecclesiasticus) 49:14: “But upon the earth was no man created like Enoch; for he was taken from the earth.” (KJV). That would leave two people in all of the old testament who did not die but were "taken": Elijah and Enoch. (And don't forget the Book of Enoch.)

“These are the two olive trees and the two lampstands that stand before the Lord of the earth.” Others say that the olive trees are the Jews, and the lampstands are the Christians.

Some Jews will think the Antichrist is the Messiah. But others will accept that Jesus is their true Messiah. Paul somewhere says that the original wild branches will be grafted back on the the original olive tree. The two witnesses may be the remnant faithful of the Jews and the remnant faithful of the Christians.

I'm not sure that I agree that "wrath" = "tribulation". There will certainly be a wrath that is poured out solely on those who reject Jesus. But I don't think that means that all Christians are exempt from all suffering. Obviously we are not. And Paul says: "Now I rejoice in my sufferings for you, and I fill up in my flesh what is lacking in regard to Christ’s afflictions for the sake of His body, which is the church." (Colossians 1:24) So Paul somehow mysteriously participates in Christ's redemptive suffering, as if there is something lacking therein -- which as been reserved to allow us to pick up the slack. So being exempt from "wrath" doesn't mean that we won't be expected to participate in some mysterious way in the redemptive suffering that is needed for the salvation of as many people as possible, that is, for the sake of His Body, the Church.