@ksjp - Can you put this snippet into the param distribute plugin file. Just place it below all the other code in the plugin and it should be ok:
(function(battler){ var distParamPlus = battler.distParamPlus; battler.distParamPlus = function(id) { if (this._dystStatParams === undefined){ console.log("Params was undefined for: " + this.name()) this.clearParamPlusDyst(); } return distParamPlus.apply(this, arguments) };})(Game_BattlerBase);Then, run your game, and let me know if your console still shows error, and if so, what the error is.
What this snippet basically does, is reassign the values that are showing up as undefined on your end. If the error is still showing up after that, I will have to investigate further..
Additionally - have you yet tried adjusting the placement of the plugin within the plugin manager thing? like, putting above/below others? :)