In the New Skool vs Old Skool trailer, I'm not certain but I figured someone on this sub would know if it's Old Raiden and Scorpion, with New Sub-Zero and Jax? :
Mortal Kombat 11 trailer - Old Skool vs. New Skool — Rectify Gaming
MORTAL KOMBAT 11 Old Skool VS New Skool Trailer (2019) PS4 / Xbox One - YouTube