I always discord my pets when training. The 30 rule isn't quite right. I find tactics over 50 needs to be within 20 of whatever you are training on, and wrestling it can be as much as 40 and you will still get gains. So what you want to do is discord the pet, then decide to discord the elemental or not depending one what you need to do to keep the skills close.
Sometimes you do have to discord the elemental, and not the pet, but before too long you should be in a position to be able to discord the pet as well. And discord on the bard doesn't need to be all that high. I was able to discord my greater dragon with only just over gm discord. Obviously the higher, the better, but it doesn't need to be legendary.