Oh...I didn't expect this thread to be necro'd. Though, I was planning on going back to the topic sooner or later, so thanks Asiacatdogblue for resurrecting it! Just out of curiosity, what made you decide to resurrect this thread?
As for everyone else, you've come up with some really good suggestions, though some of them don't really work for what I want, and for the others, I would need some more info on how to use them in my setting.
So, here's a bit more info on the setting for my story. I am still working on most of the details of it (I may open up another thread in the near future to discuss them), so I will just give you the basic gist of it. I hope that will be enough to convey my idea through, but questions and suggestions are always welcome.
@Sand Josieph: There are three types of magical girls (and boys) operating in my story. They are:
-The Celestials, a 200-300 (or maybe slightly more) strong organization of magical girls with powers derived from the planets. Think of it as a mix between Sailor Moon's Moon Kingdom with quite a few elements from Nanoha's TSAB. They are divided into various factions, depending on planetary alignment (which I still have to work out) and power level. The Priestesses are the leaders of the Celestials and their magically strongest warriors, having inherited the powers of their planet in their purest form. Their power levels are usually quite strong, almost equalling or exceeding Nanoha's. The latter, except in certain cases, are usually sent to battle their enemies IN SPACE!, and stop the bulk of their forces from invading Earth. The Warriors are not as powerful, but a team of them can usually hold off and defeat the monsters of the week without external aid.
Of the three main groups, the Celestials, and especially the Priestesses, are the more traditional group, so a vast majority of them still have wands and staffs as their weapons, tend to have long transformation sequences (the Warriors have significantly shorter ones due to the fact that they have to strike first and protect the priestesses), and still do In The Name Of The Moon Speeches, though they are genre savvy enough to include a couple of damage control and targeting spells in said speeches, as well as have the warriors strike first without said speeches to allow the Priestesses to complete their spells.
-The Infernals, a catch-all term for all the magical forces that, for one reason or another, want to take control of Earth. Their overall goal is to conquer the Earth, enslave it's population, take control of magical resources, defeat the magical girl 'immigrants' from other planets that have arrived on Earth, and other such things, though for most of them their main objective is to defeat the Celestial and/or find the portal that leads to their Temple on Jupiter to attack them and remove the blockade caused by the Celestials in space. Except for some rare cases, they usually used to act like your typical magical girl enemy, but in the last couple of decades, they have started recruiting Terrans in their ranks, and have somewhat become more genre savvy, which has lead to the Celestials recruiting Terrans as Celestial Warriors, and the formation of several investigative teams amongst the Celestials to hunt the Infernals down and strike first before they can cause damage.
-The Terrans, a catch-all term for a rapidly growing faction of magical girls and boys gifted with a spark of power from mother Earth herself. They mainly manifest as mutants and were-creatures, though, if they are luck enough to get a hang on an elemental power, or any other source of power (the energy from a long-lost kingdom, for example), they can reach the power levels of the Warriors, and sometimes even the Priestesses. Due to this factor, Infernals and Celestials have started recruiting these Terrans in their ranks, telling them they are actually warriors from their faction instead of Terrans with an external aid. Those that are not recruited in either the Celestial or Infernal ranks tend to form their own small groups, with various degrees of genre savvyness and training depending on the individuals forming it. There are, however, some more organized groups that fight both Infernals and Celestials, the former because, well, they are invaders: and the latter because they consider them also invaders, and because the Priestesses put a curse on Earth to stop the birth of an Earth Priestess, as the last one went on a rampage to kill all the 'polluting' humans, and they don't want to risk that happening again (although some claim it was just a convenient excuse to rid themselves of what they see as a wild card and a threat to their power).
TL;DR: there are a wide variety of magical girls, each with their own issues and reasons to fight.
As for why they need to die, well, each faction has done some questionable acts on Earth civilians that has motivated the magical girl hunter team to hunt them down and kill them all. For example, Alyssa had a few friends from different school factions (such as an unpopular girl and a member of the Girl Posse), and the Libby and other people put a lot of peer pressure to put them apart, maintain the status quo, and shun Alyssa. So Alyssa basically set off to break the Libby and utterly destroy that status quo, just so that she could stay with her friends. One day, the Libby came back with an Infernal, who turned said Libby into a monster that killed off some of Alyssa's friends, while another of her friends was caught in one of the Celestial's killer attacks. Alyssa, who likes to have everything under control, sees these girls and their fight as a threat to her perfectly controlled worlds, and so sets out to remove them all from the equation.
Now, as for the magical girl hunter team, I was thinking about having them as a renegade cell of a bigger organization, or a group with people from different professions coming together after an incident with magical girls, or something along those lines. The reason I want that is because, later on in the story, it turns out that the original team once went up against a Priestess and got owned, only for said priestess, after a through interrogation, decide to sponsor/blackmail them in killing Terrans, Infernals, and Celestial political enemies, so I don't want their parent group to become too suspicious.
So, the thing I need to work out now is what kind of team could provide which kinds of solutions towards the magical girl killing, as well as a decent clean up operation. The 'solution' must also be pretty clean and reliable, and done in such a way as to not really leave an easy pattern or trail for the magical girls to follow. Of course, Terrans and Infernals don't really share information between them, and most Celestial investigators are being kept in check by the group's 'sponsor', but Alyssa and the group want to play it safe, and the group does not want Alyssa to find out about their agreement with the Celestials, due to the fact that she has a tendency to go for disproportionate retribution, and they fear she might not like what they have done.
So, having said that, which of the solutions you have proposed could suit my requirements? And what kind of group members am I looking for to justify everything?
@Omnis: The kill team is usually familiar on who their targets are in MG form. Information on their civilian form depends on how careful the individual is (Alyssa' first target's identity was found out using Facebook) and how dedicated their chosen faction is to uphold the Masquerade (the Celestials usually do a great job at it, with mind wiping and websites only magical people can see). Anyway, you have pretty much come up with most of the tactics I plan to include in the story. If you could now explain to me how to justify the team getting the hands on all that equipment to put their plans into action, then that would help me quite a lot.