Did try it, the battle core plugin is heavily dependent on draw windows... Thanks anyways! Will wait for others in case others also have solution on this

Appreciate the help though
@estriole !
try this code snippet
Code:
var Game_Enemy_battlerNameWeakEnemy = Game_Enemy.prototype.battlerName;
Game_Enemy.prototype.battlerName = function() {
return Game_Enemy_battlerNameWeakEnemy.call(this) + this.battlerSuffix();
};
Game_Enemy.prototype.battlerSuffix = function() {
this._battlerSuffix = "";
if (this.hp <= this.mhp * 50/100 && this.getRequireSuffix()) this._battlerSuffix = "_weak";
return this._battlerSuffix;
};
Game_Enemy.prototype.getRequireSuffix = function() {
if (!$dataEnemies[this._enemyId]) return false;
if (!$dataEnemies[this._enemyId].note.match(/<weak_form>/im)) return false;
return true;
};
tag your enemy that have weak form in the notetags with <weak_form>
then in your img/sv_enemies folder... add the weak enemy image with same name as enemies but added _weak at the end.
ex:
Gnome.png
Gnome_weak.png
this is simple code snippet though... it also only have one "weak form" at below 50% max hp...
if you want to change it to 10% for example... change the 50/100 to 10/100 (don't use 10% because it will throw error. % is not percent in javascript code but modulus)
and i did not test it extensively. tell me if you encounter any problem.
if you need multiple "weak" form (example change at 50%, 30%, 10%) tell me about it and i will add the code.
hope this help.
edit: modify the code a little bit to use alias instead of overwrite to avoid incompatibility.
edit2: i made it a proper plugin instead.
■ Information ╒══════════════════════════╛ EST - ENEMY IMAGE CONTROL MZ Version: 1.0 By Estriole File name: EST_ENEMY_IMAGE_CONTROL.js ■ Introduction ╒══════════════════════════╛ This plugin is for changing the enemy battler graphic when the certain condition are met... ■ Features...
forums.rpgmakerweb.com
it support multiple stages of weak form... as much as you want... you can add it in plugin parameter

.
hope this help.