The starting party in the NES version consists of 2 Knights, 2 sorcerers, cleric and thief.

I haven't played MM1, so I can't comment on what the game actually *requires*, but any party that has both types of magic and a Robber *should* work. This could also be said to be true for MM2-5 as well.

Anyway, here are the minimum party requirements for MM2-5, assuming the following rules:
* No reliance on random treasure. (Random treasure can replace missing spells, but only if you are lucky enough to find it, and I think most players wouldn't find it fun to reload until an item that can cast a specific mandatory spell shows up.)
* No using any "cheat" codes in the mirror for the games that have them. (For example, no using it to warp straight to the final boss.)

MM2: Your party must contain at least one non-Robber. The game can be beaten with only Robbers in the final party, but you will need to bring along a member of another class to complete a certain quest. (Oddly enough, this game is shorter if your party has less class diversity; the more different classes in the party, the longer it takes to beat the game.)

MM3: I believe Walk on Water is almost required, so you will need a Druid or Ranger. (I note that the default party contains neither class.) There is a way to get Thievery on arbitrary characters, and it can be done without needing to already have the skill (though it's not recommended for a first play through).

MM4: Teleport is required, so you need a Sorcerer or Archer. (For some reason, that spell is not on the Druid list, even though it costs less than 11 SP; considering that the spell is actually required, I consider that bad game design.) (Is Thievery required? If so, you also need a Robber or a Ninja. Even if it isn't required, I would still recommend taking one along.)

MM5: Jump is required. Fortunately, that spell *is* on the Druid list, so your party just needs one out of Sorcerer, Archer, Druid, or Ranger. (Again, is Thievery required?)

Swords of Xeen: I don't remember any spell required here (though my memory could be wrong). I note that Thievery is *not* needed in this game and is pretty much useless.

I have not played any later games in the series, so I don't know if there are any similar requirements regarding party composition in those games. (Apparently, at least some of them have a Fly spell; is that spell required?)

I would not recommend skipping a Sorcerer. The high-level Sorcerer and Cleric spells are really useful, so I'd have at least one of each in the party. I also consider a Robber essential, since nearly all of the equipment you'll use will be found after battles in trapped chests and you need a Robber to open them safely. The remaining three spots in the party can be more flexible.

Having said that, you could try other parties for an added challenge. I can't remember if Archers and Paladins ever get spells past tier 4; if not, the game would be very challenging if they're your only spellcasters, but it might be interesting too. A magic-heavy party might be tough early on when spells are weak, but could become really powerful later, provided you don't run out of gems.

I should note that I went with one of each class when I played, so I haven't tried any of these other parties myself.

Archers and Pallys are topped out at four so it would indeed be a challenge and one I would look into after a couple other combos are attempted.

The 2nd cleric in place of the Pally is working out well right now. The Pally in my first run through really sucked as a fighter even with a 16 might and a 16 personality. I not sure how important accuracy is for the other classes but the 12 the Pally had, if it mattered didn't seem to do too much. My 2nd cleric hits just as easily and the extra healing really helps in those long sustained battles.

I'm starting to create Knight, Robber, 2 Cleric, 2 Sorcerer setup to see how over powered that group is in the end game.

I'm also considering not using a robber just to see how tough bad can get without someone to diffuse traps.

As a kid I always played MM1 without a robber. I just accepted trap damage as part of adventuring. I never completed the game, though, so it's possible a robber is essential at some point.

I took along a second archer, and placed them both in positions 5 and 6 of my party. They could often pick off dangerous monsters while they were out of hand-to-hand combat range.

I recall situations where traps could kill my party, even if they rested first. But it's possible those situations are rare, such that going without a Robber is feasible. I also wouldn't be surprised if this depends on which version of the game one plays; I know versions on other systems often had major differences.

One nice thing about Archers is that they can shoot at enemies even if the Archers themselves are stuck in melee range. So it's not necessarily the best idea to put them in the back; I typically kept my spellcasters there to keep them a little safer. Archers could be near the front and still shoot at distant enemies.

I get tired of being poisoned so I don't think I would give up the robber. Though it isn't too bad when you got the money or spell points, it is a waste of time.