balistic products carries super buck   (2000 catalouge  763 494 9237). ,,, b is .17, bb .18, ,bbb .190,,t .200,,tt .210,f .22,, 4.240,,3 .25... for geese they used  2 and bb in the old days with good results, it brings it down not usually kill it.. but hiiting the ground usually would.  i think you need to be in about the  f range or .22  diameter.. could take some real testing on the critters.. youll be needing a body shot, wich will need tracking with little or no blood trail, or head shot, and belive me the yotes skull is thick.. so youve got quite a job ahead of you to figgure out what will work.  some guys have used number 4 buck, but havent heard much on results..    a deer sized critter can be had with .45 cal thats  about  one grain per pound..   a yote im guessing (ive carried plenty) will weigh in at about 15-30 pounds, lets say 20 average dont kknow. but a 15 grain ball would be about  f shot or .220 diameter ,  28 pellets an ounce.. i would try that..  number 4 has 20 pellets an ounce or 21 grains, and  tt has 29 pellets and ounce and t has 31 pellets an ounce..  good luck dave.. by the way it will be about 15-2o bucks or more for a  8 lb jar  of shot if they still have it.. ....  at 20 yards f may turn him inside out which is pretty much what your going to need to do..  id order a jar of f and number 4 buck and try them each and see what happens and  let us know.. dave..