It's still unknown whether the X-Men appearing in Avengers: Doomsday will be the same as those from the Fox universe, but there would be a contradiction if they were.

They can't be from Earth-10005 because Mystique died in 1992 during the events of Dark Phoenix, and Charles died during the events of Logan. However, I theorize that there's a possibility they're from the Wolverine universe of D&W. In that film, he recounts a massacre at the Mansion where several X-Men died. This would explain why only a few will appear (based on what we know so far) and why the teaser shows the Mansion dilapidated and abandoned, as it has been closed since that day. Furthermore, this Wolverine made it clear that his X-Men wore the classic costumes.

They could also say that this universe is involved in the Multiversal disaster, because they lost their Wolverine (who went to live on Earth 10005) generating another incursion in addition to Monica's.

Something also tells me that in the movie they're going to say they're the same people, creating contradictions, like they did with D&W, where they say the movie takes place in 2024 and Logan is already dead, even though he dies in 2029. I hope they don't do this and just say they're different.
(Theory) What universe are the X-Men from Avengers Doomsday from?