AJ: YOU WANT ME TO PUT THE HAMMER DOWN!? (Yes I took the quote from Thor.)
I have several ideas for each of them; AJ's "Keg-hammer" Contains a store of high-proof liquor. If needed (and if she doesn't drink it all first, a hit from the hammer can soak the opponent in flammable alcohol…But how to light it?
Fluttershy is described as a "Tamer", so I assume she's more in tune with nature. And since she's well-versed in medicine, I assume she'll know how to concoct tranquilizers or poisons for her arrows…and of course, summon help from allied animals. (Angel's Wrath would be HILARIOUS when you think about it. A tiny bunny rabbit kicking the shit out of an enemy)
Rarity's weapons could be diamond daggers disguised as a decorative brooch? It would certainly fit her affinity with gems and beauty…that, or a needle-gun (note: The needle gun would be even more effective if the Illusionist was an expert of acupuncture, as one needle to the spinal cord would cause serious harm.)
However, if the Illusionist is Trixie, then use poisons (Hallucinogenic, fast-acting, you know the drill.)