Three sets of rival owners have played over 50 regular season games in this series, and 23 sets of rival owners have at least 40 regular season games:
ashleyscott v. ncih - 55 games
ashleyscott v. pharrop - 53 games
pharrop v. tgrunewald - 52 games
captainzen v. ncih - 48 games
jethroeg v. joshbonds - 48 games
ashleyscott v. tgrunewald - 47 games
joshbonds v. ncih - 47 games
jakotay v. sweg - 46 games
ashleyscott v. captainzen - 45 games
jakotay v. ncih - 45 games
jakotay v. thebigrec - 45 games
ashleyscott v. thebigrec - 44 games
jakotay v. mrbrzys - 44 games
mrbrzys v. ncih - 43 games
pharrop v. sweg - 43 games
jethroeg v. tgrunewald - 42 games
jakotay v. pharrop - 41 games
ncih v. thebigrec - 41 games
ashleyscott v. usmoo_87 - 40 games
bsmuke v. ncih - 40 games
captainzen v. jethroeg - 40 games
captainzen v. pharrop - 40 games
captainzen v. thebigrec - 40 games
My record of who won those games only goes back to Gym Rat VIII unfortunately.
ashleyscott v. ncih - 9 - 5
ashleyscott v. pharrop - 15 - 3
pharrop v. tgrunewald - 17 - 2
captainzen v. ncih - 4 - 3
jethroeg v. joshbonds - 7 - 6
ashleyscott v. tgrunewald - 12 - 6
joshbonds v. ncih - 2 - 4
jakotay v. sweg - 9 - 10
ashleyscott v. captainzen - 7 - 5
jakotay v. ncih - 3 - 4
jakotay v. thebigrec - 6 - 3
ashleyscott v. thebigrec - 10 - 2
jakotay v. mrbrzys - 2 - 0
mrbrzys v. ncih - 1 - 7
pharrop v. sweg - 2 - 4
jethroeg v. tgrunewald - 7 - 6
jakotay v. pharrop - 4 - 2
ncih v. thebigrec - 7 - 5
ashleyscott v. usmoo_87 - 12 - 6
bsmuke v. ncih - 4 - 6
captainzen v. jethroeg - 15 - 4
captainzen v. pharrop - 11 - 7
captainzen v. thebigrec - 3 - 4