Bookwyrm627: MM6:
-Cleric and Sorcerer are out because they give access to Light/Dark with their improved Day of Gods, Day of Protectin, etc.
-Paladin does most things a Knight does and adds Self magic, so no Paladin.
-Archer gives somewhat more limited to Elemental magic (Fly, Water Walk, Town Portal, Beacon, etc), so they are out.
-Druid gives both Self and Elemental.

Process of elimination says that 4 Knights is probably the hardest (most tedious) party.

MM7:
-Cleric and Sorcerer are obviously out.
-Paladin, Archer, and Druid give Mastery in Self, Elemental, or Both, so they are out.

That leaves the Knight, Thief, Monk, and Ranger.
-The Knight, Thief, and Monk can all GM differing selections of combat skills, while the Ranger can only GM Axe and M Bow and Leather/Chain.
-The Knight fixes broken gear and can GM both Body Building (scrolls of Shared Life) and Armsmaster (damage).
-The Thief can GM Disarm Trap (and a Ninja can M it), both Monk and Thief can M Armsmaster, and Monk can GM Body Building.
-The Ranger can do just about anything, but there are very, very few things it does well. It does have Expert Self and Elemental, but speaking from experience, that's almost more of an insult than a help.

I'm thinking 4 Rangers is probably the hardest (most tedious) party.
Alternatively, maybe some combination of Thieves and Monks on the Dark path to reduce magic availability without getting the physical damage and durability boost of using Knights.

MM8:
-No dragons, obviously. Also, no Necromancer or Cleric. I figure these restrictions are self-explanatory.
-The Dark Elf and Vampire bring Master Elemental and Self magics, so they are out.

That leaves the Troll, Knight, and Minotaur.
-Speaking from experience, Trolls are insane melee warriors with a mace. They don't really do much besides regenerate, have hp, and swing a mace, but that is just means they have more skill points to put in Mace to increase the Paralyze On Hit chance, and having a 30% chance of effectively removing a monster from combat with each hit is crazy good.

Therefore, some combination of Knights and Minotaurs is the way to go. Use the level 15 and 30 versions (Thanys, Rionel, Leane, and Nelix) when you can pick them up because those have more skill point wastage than you would have when raising it from low levels yourself. This party will still be very good in turning melee monsters into corpses, and Minotaurs eventually bring Expert Self magic, but I think that's the best you can do in getting a "bad" party in this game. The other classes just bring so much more utility and Quality of Life abilities to include.