The elite pony packs in WHIMSYSHIRE can be extremely annoying due to their speed, but i found a spot where you can kill any Pony pack with ease. This is very map dependant, it doesnt always spawn.
You simply need to get to the spot in my attachment. Which is a Kitten icon, with a little "cloud" above it
1. You kite the mobs around the little tree, so they are positioned between it and the edge of the map - The red cirkle.
2. Once you got them there, you simply position yourself at the blue cirkle and nuke them out of range. If you stand right, it will prevent mobs from throwing mortars, and stuff as shielding, so you pretty much just stand still and dps, and equip your MF gear at low % if your dps is high enough to dps them, as they will be healing abit.
Extra notes: This only works for the Pony packs, flowers and the bears can simply walk trough this spot. I did not test the little ponies yet, but im 99 % sure they wont work either.
Hope this is usefull for someone and isnt a repost!