Dispel has been discussed as a possible counter, though if you really NEED to run any card in your deck just to counter a single other card that generally is proof alone that the card your countering needs to be toned down. The issue though as you touched on is that its not a starter card nor is it a common or uncommon, but in fact a rare (3 star). That means the odds of you acquiring one are very low, ridiculously low if you don't spend any real money, and for those who don't have a visa/mastercard spending real money isn't even an option they have available to them.
Now if you wanted to say, gift a single copy of Dispel to everyone whose played so far, I wouldn't complain and it might decrease Killing Machine abuse a little bit, but as things stands its not a viable option for the VAST majority of players since the vast majority quite frankly don't have one and don't have a viable means to get one in the near future.
I've personally thought about using the Assassin soul skill, to be sure as long as you can keep atleast one unit out it will completely stop both Killing Machine and the revivers, but timing its activation at the right time is even trickier then using Killing Machine (you need to not only make sure you have a friendly unit out, but that it doesn't go off before they have a killing machine'd unit out). Whats more, against decks that don't run killing machine, its quite frankly not a very good soul card for the average deck. Its terrible against swarm decks and often hurts you just as much if not more then an opponent if you yourself are not using a low SP cost unit swarm deck. Your once again weakening your deck just to stop a single card, which again speaks to the fact that that single card is probably too strong if such a thing is even being considered.
Again I don't necessarily hate such a powerful effect existing, there are ways it can be stopped, I just hate that its so easy to pull off, something that provides that large of an advantage should require much more set up or have a much greater disadvantage to the user. The fact that many of the best ways to stop it aren't available to the average user doesn't help things either.
The bunnies of Lavato have special abilities, like 'Action Skill: Make Carrot Disappear.'