After some investigation I come to this conclusion:
Visustella Skill Cost Types -> Draw Gauge takes precedence over MK plugins regardless of plugin order, and they failed to write their functions in a way that other plugins like mine can still take actions. For the moment you can do the following:
In the Plugin Manager, go to Visu Skill States Core -> Skill Cost Types -> for HP, MP, TP respectively -> JS: Draw Gauge, and paste this:
// Declare Variables const sprite = this; // Draw Gauge sprite.drawGauge() // Draw Label sprite.drawLabel() // Draw Value sprite.drawValue()
This basically tells VS to undo their modifications to the core code.
I will think about a better solution, though.