Arguably, you will never need more than 3 of any specific breed of any given pet (outside the Celestial Tournament, rarely), but having NEVER used a rabbit because of it's damage impact, and using them frequently for trainers, legendaries, Celestial Tournament, and even on some of the Tiny Terrors because of their dodge/burrow mitigation, I stand by the statement. There are far far better critters to use to dispatch undead if you don't need the mitigation of a bunny.
You may never need more than a couple s/s bunnies, but I doubt you will ever find yourself NEEDING a non-s/s breed rabbit as the "best breed" for any opponent.
As for moths... I'd be impressed if someone managed to have all eleventybillion moths in the P/S breed. That's just silly (and some moths, like the Yellow or the newer ones with Call Lightning are better in non-p/s breed). Get 2 P/S moths and you are golden. For most enthusiasts, the rest are likely whichever breed you first encountered as a capturable rare.
I also have a b/b crow I far prefer to the s/s crow 90% of people recommend simply because he hits a bit harder and has an extra round or two of survival in 'im. I don't encounter too many opponents a crow's racial doesn't make it faster than when it counts.
Again, as per the original responses, it's all subjective to the opponent. Breeds matter far more in PvP and Celestial Tournament. I don't know too many wild battles or trainers where breed much affects the outcome (yes, there are several trainers where breed removes RNG-potential-resets or additional rounds, but you can still win with the same moveset).