Complex sentence: In this match whoever gained the first pinfall and submission would advance to the Round of 16 and would exit the match, the remaining 2 participants would then go 1-on-1 for the right to advance.
Split into simpler sentences: In this match whoever gained the first pinfall or submission would advance to the Round of 16 and would exit the match. The remaining 2 participants would then go 1-on-1 for the right to advance.