Once upon a time some of my students were into Warhammer and wanted to have a Warhammer battle with their overpriced figures after school. So we had a bring and battle including all kinds of misfit miniatures. We didn't use the Warhammer rules, though. We used these which are super basic.
Sequence of play is move, shoot, opponent move, opponent shoot, both sides charge
All units will be classified as one of the following:
Shooters: Any unit with ranged weapons like arrows, guns, crossbows
Warriors: All units that fight on foot with melee weapons
Riders: Any unit mounted on horses, boars, etc.
Leaders: Special individual leader figures, on foot or mounted
Artillery: cannons, bolt shooters, etc.
Small Monsters: Trolls, chariots, small war machines, etc.
Large Monsters: Giants, Dragons, large war machines, etc.
Unit Size: Shooters, warriors, and riders have 6 figures per unit. Artillery should have 4 crew. All other units have a single figure/model.
Elite units: Some warrior and rider units may be designated as elite. The melee number for elite units is one better than for regular units. Regular units must outnumber elite units by at least 2 – 1.
Sm Monsters: roll 3 dice, hit on 4-6, takes 4 hits to kill them
Lg Monsters: roll 3 dice, hit on 4-6, takes 8 hits to kill them
Artillery 6 (crewmen get to fight, lose 1 die when firing for each crewmen lost)
Shooters 0-12” hit on a 6
Artillery 0-24” roll 3 dice, hit on 4-6
Movement: Riders move and charge 12”, everyone else moves and charges 6”.