Surprisingly many...

Makuhita: Can go for 94% Strength range (saves 2 inputs, and better to miss range than miss Mud Shot)
Spinda: Can Strength + Mud Shot (97% 2HKO, 9/16 crit OHKO)
Zangoose: 65-->82% OHKO
Vigoroth: 53-->59% OHKO
Slaking: Improve Mud Shot ranges at -0 and -1
Grovyle: 94-->100% OHKO
Altaria: 53-->65% OHKO at +3 (probably only worth going for if Perish Song)
Gyarados: Improve Strength 3HKO range

Saves ~8 seconds on average, but it takes slightly longer to get + use it. Still a very good marathon strat because it allows you to skip saving for Rival 3.