Generate a YGOPro Lua script for the following Yu-Gi-Oh card effect:
2 Level 2 monsters When your opponent Normal or Special Summons a monster(s) (except during the Damage Step): You can detach 1 Xyz Material from this card; that monster(s) loses 500 ATK.
--シャインエルフ
--Shining Elf
local s,id=GetID()
function s.initial_effect(c)
	--xyz summon
	Xyz.AddProcedure(c,nil,2,2)
	c:EnableReviveLimit()
	--atkdown
	local e1=Effect.CreateEffect(c)
	e1:SetDescription(aux.Stringid(id,0))
	e1:SetCategory(CATEGORY_ATKCHANGE)
	e1:SetType(EFFECT_TYPE_FIELD+EFFECT_TYPE_TRIGGER_O)
	e1:SetCode(EVENT_SPSUMMON_SUCCESS)
	e1:SetRange(LOCATION_MZONE)
	e1:SetCost(Cost.DetachFromSelf(1))
	e1:SetTarget(s.target)
	e1:SetOperation(s.operation)
	c:RegisterEffect(e1)
	local e2=e1:Clone()
	e2:SetCode(EVENT_SUMMON_SUCCESS)
	c:RegisterEffect(e2)
end
function s.filter(c,e,tp)
	return c:IsFaceup() and c:IsControler(1-tp) and c:GetAttack()>0 and (not e or c:IsRelateToEffect(e))
end
function s.target(e,tp,eg,ep,ev,re,r,rp,chk)
	if chk==0 then return eg:IsExists(s.filter,1,nil,nil,tp) end
	Duel.SetTargetCard(eg)
end
function s.operation(e,tp,eg,ep,ev,re,r,rp)
	local g=eg:Filter(s.filter,nil,e,tp)
	local tc=g:GetFirst()
	for tc in aux.Next(g) do
		local e1=Effect.CreateEffect(e:GetHandler())
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_UPDATE_ATTACK)
		e1:SetValue(-500)
		e1:SetReset(RESET_EVENT|RESETS_STANDARD)
		tc:RegisterEffect(e1)
	end
end