Mission name: Tension between Countries
Mission rank: A-Rank, Repeatable
Objective: Stop a group of war enthusiasts
Location: Kaminari no Kuni Border (Kumogakure)
Reward: 500 Ryo
Mission description: The Raikage has been tracking a group of mercenaries and criminals who are encouraging war between their country of origin and Kumogakure. They are nearing the border, and it's your job to stop them before they invade the village.
Mission details: These mercenaries are all of Chuunin-Rank, but there are a total of 30-40 of them (may be any number between those, the choice is the yours). They may be from whatever village (other than Kumogakure no Sato) you want, but they all must be from that village, and they will be outfitted in the flak jackets of said village. It is up to you whether to kill them or repel them, but if they successfully invade, the mission is a failure.

Name: Mercenary
Age: 24-50
General Appearance: Varies, but they are all outfitted in the traditional flak jackets of their village (and therefore gain the benefits of said armor), and they also each carry a fuma shuriken.
Personality: Rebellious and loud, very violent and bloodthirsty.
Motivations: To destroy Kumogakure, or start a war between Kaminari no Kuni and their country of origin.
Fears: Peace?
Other: Their specialties and elements may vary, but their primary will be B-Rank, and their secondary will be D-Rank, and both of their elements will be C-Rank. None of them have tertiary element or spec, and those that possess Bukijutsu carry one C-Rank weapon of choice.

So....all of them are Jounin-rank? Since they have access to an S-rank spec. I don't think that you can do this without a full 4-man squad. Hell, I wouldn't let you do it with only TWO squads. These are powerful shinobi you're fighting against. 75 of them, no less. Tone down their rank or their numbers. Passing this mission is unrealistic without a substantial amount of people.

Cut their numbers in half, and also cut down their specs and elements. They're weak enough to get obliterated now. :)

Finished the mission here.