ouch...
With or Wihout playmaker, this is going to be tricky.
I would start with the following:
-- design a prefab for each piece,
-- Implement the logic of movement ( with no rules)
-- implement rules ( with no impact on the game, just a rule with input and output ( true or false)
then you combine all of that.
Do you want to do a chess engine? or a validator for player movements? that's two very distinct project actually..
bye,
Jean