I will go with Izyees' solution. It doesn't need a big script to do this.
Assuming they're not using Yanfly's Battle Engine already perhaps, but I find it silly to keep an image you don't need just to stop drawing shadows when you can just comment out one or two lines.
You could change the code in rpg_sprites.js for the following:
Find this:
Sprite_Actor.prototype.initMembers = function() {Sprite_Battler.prototype.initMembers.call(this);this._battlerName = '';this._motion = null;this._motionCount = 0;this._pattern = 0;this.createShadowSprite();this.createWeaponSprite();this.createMainSprite();this.createStateSprite();};Change it to:
Sprite_Actor.prototype.initMembers = function() {Sprite_Battler.prototype.initMembers.call(this);this._battlerName = '';this._motion = null;this._motionCount = 0;this._pattern = 0;this.createWeaponSprite();this.createMainSprite();this.createStateSprite();};and then find:
Sprite_Actor.prototype.update = function() {Sprite_Battler.prototype.update.call(this);this.updateShadow();if (this._actor) {this.updateMotion();}};
and change it to:
Code:
Sprite_Actor.prototype.update = function() {Sprite_Battler.prototype.update.call(this);if (this._actor) {this.updateMotion();}};