Here are some things to get you started. The machines will be divided into classes and further divided into models. Here are a couple classes of mechs I'd like to see:

Standard Mechs: legs attached to body (i.e. MechWarrior), very maneuverable, light armor, lighter weapons

Tread Mechs: roll on tank-like treads, less maneuverable, heavier armor, heavy weapons

Tanks: slow, very heavy armor and weapons

Hovercraft: fast, heavier armor and weapons, poor handling

We need mechs specifically designed for different tasks: probing, defense, siege, close combat, etc. Also remember that all mechs will be playable, so try to think of several different moves/abilities they might have.

-Nag