Hey hey, long time.

I am currently using Moogle Xs Equip Skill plugin to drive battle skills and wanted to set the skill needed to be equipped by the dual tech actors as an additional requirement for dual techs showing in battle. 

I am pretty sure I've identified the function `Game_Actor.prototype.eqsSkillEquipped = function(skill)` in their plugin that I would need to hook to, but I am uncertain how to add that to your plugin to make it a part of meetsSkillConditions. 

Any help?

I'm surprised they didn't update meetsSkillConditions themselves. Would have been a godsend for compatibility.

I honestly don't know if anything simple I write would be compatible with that plugin due to that, but try adding this in a patch after their plugin:

var skillConditionPatch = skillConditionPatch || {};
skillConditionPatch.meetsSkillConditions = Game_BattlerBase.prototype.meetsSkillConditions;
Game_BattlerBase.prototype.meetsSkillConditions = function(skill) {
   if (this.isActor() && !this.eqsSkillEquipped(skill)) {
      return false;
   }
   return skillConditionPatch.meetsSkillConditions.call(this, skill);
};

And I make no promises; this is untested. If that doesn't work... well, all due respect? I'm not rewriting my plugin just to deal with a plugin that wasn't really made with general compatibility in mind that may have been abandoned over seven years ago.

EDIT: Another possibility would be to patch eqsSkillEquipped.