Gadarla,
You can Special Summon this card (from your hand) to your opponent's field in Attack Position, by Tributing 1 monster they control. If your opponent controls a "Kaiju" monster, you can Special Summon this card (from your hand) in Attack Position. You can only control 1 "Kaiju" monster. Once per turn (Quick Effect): You can remove 3 Kaiju Counters from anywhere on the field; the ATK/DEF of all other monsters on the field become halved.
local SETCARD_ID_0 = 0xd3 --Kaiju
local COUNTER_ID_0 = 0x37 --Kaiju

local SETCARD_ID_0 = 0xd3 --Kaiju
local COUNTER_ID_0 = 0x37 --Kaiju
local s, id, o = GetID()
function s.initial_effect(c)
	c:SetUniqueOnField(1, 0, aux.FilterBoolFunction(Card.IsSetCard, SETCARD_ID_0), LOCATION_MZONE)
	--special summon rule
	local e1 = Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_SPSUMMON_PROC)
	e1:SetRange(LOCATION_HAND)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE + EFFECT_FLAG_SPSUM_PARAM)
	e1:SetTargetRange(POS_FACEUP_ATTACK, 1)
	e1:SetCondition(s.spcon)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
	local e2 = Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_SPSUMMON_PROC)
	e2:SetRange(LOCATION_HAND)
	e2:SetProperty(EFFECT_FLAG_UNCOPYABLE + EFFECT_FLAG_SPSUM_PARAM)
	e2:SetTargetRange(POS_FACEUP_ATTACK, 0)
	e2:SetCondition(s.spcon2)
	c:RegisterEffect(e2)
	--Halve ATK
	local e3 = Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id, 0))
	e3:SetCategory(CATEGORY_ATKCHANGE + CATEGORY_DEFCHANGE)
	e3:SetType(EFFECT_TYPE_QUICK_O)
	e3:SetCode(EVENT_FREE_CHAIN)
	e3:SetRange(LOCATION_MZONE)
	e3:SetProperty(EFFECT_FLAG_DAMAGE_STEP)
	e3:SetHintTiming(TIMING_DAMAGE_STEP, TIMING_DAMAGE_STEP + TIMINGS_CHECK_MONSTER)
	e3:SetCountLimit(1)
	e3:SetCondition(aux.dscon)
	e3:SetCost(s.atkcost)
	e3:SetTarget(s.atktg)
	e3:SetOperation(s.atkop)
	c:RegisterEffect(e3)
end
function s.spfilter(c, tp)
	return c:IsReleasable(REASON_SPSUMMON) and Duel.GetMZoneCount(1 - tp, c, tp) > 0
end
function s.spcon(e, c)
	if c == nil then
		return true
	end
	local tp = c:GetControler()
	return Duel.IsExistingMatchingCard(s.spfilter, tp, 0, LOCATION_MZONE, 1, nil, tp)
end
function s.sptg(e, tp, eg, ep, ev, re, r, rp, chk, c)
	local g = Duel.GetMatchingGroup(s.spfilter, tp, 0, LOCATION_MZONE, nil, tp)
	Duel.Hint(HINT_SELECTMSG, tp, HINTMSG_RELEASE)
	local tc = g:SelectUnselect(nil, tp, false, true, 1, 1)
	if tc then
		e:SetLabelObject(tc)
		return true
	else
		return false
	end
end
function s.spop(e, tp, eg, ep, ev, re, r, rp, c)
	local g = e:GetLabelObject()
	Duel.Release(g, REASON_SPSUMMON)
end
function s.cfilter(c)
	return c:IsFaceup() and c:IsSetCard(SETCARD_ID_0)
end
function s.spcon2(e, c)
	if c == nil then
		return true
	end
	local tp = c:GetControler()
	return Duel.GetLocationCount(tp, LOCATION_MZONE) > 0 and Duel.IsExistingMatchingCard(s.cfilter, tp, 0, LOCATION_MZONE, 1, nil)
end
function s.atkcost(e, tp, eg, ep, ev, re, r, rp, chk)
	if chk == 0 then
		return Duel.IsCanRemoveCounter(tp, 1, 1, COUNTER_ID_0, 3, REASON_COST)
	end
	Duel.RemoveCounter(tp, 1, 1, COUNTER_ID_0, 3, REASON_COST)
end
function s.atktg(e, tp, eg, ep, ev, re, r, rp, chk)
	if chk == 0 then
		return Duel.IsExistingMatchingCard(Card.IsFaceup, tp, LOCATION_MZONE, LOCATION_MZONE, 1, e:GetHandler())
	end
end
function s.atkop(e, tp, eg, ep, ev, re, r, rp)
	local c = e:GetHandler()
	local tg = Duel.GetMatchingGroup(Card.IsFaceup, tp, LOCATION_MZONE, LOCATION_MZONE, aux.ExceptThisCard(e))
	local tc = tg:GetFirst()
	while tc do
		local atk = tc:GetAttack()
		local def = tc:GetDefense()
		local e1 = Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_SET_ATTACK_FINAL)
		e1:SetValue(math.ceil(atk / 2))
		e1:SetReset(RESET_EVENT + RESETS_STANDARD)
		tc:RegisterEffect(e1)
		local e2 = Effect.CreateEffect(c)
		e2:SetType(EFFECT_TYPE_SINGLE)
		e2:SetCode(EFFECT_SET_DEFENSE_FINAL)
		e2:SetValue(math.ceil(def / 2))
		e2:SetReset(RESET_EVENT + RESETS_STANDARD)
		tc:RegisterEffect(e2)
		tc = tg:GetNext()
	end
end


Gadarla,
You can Special Summon this card (from your hand) to your opponent's field in Attack Position, by Tributing 1 monster they control. If your opponent controls a "Kaiju" monster, you can Special Summon this card (from your hand) in Attack Position. You can only control 1 "Kaiju" monster. Once per turn (Quick Effect): You can remove 3 Kaiju Counters from anywhere on the field; the ATK/DEF of all other monsters on the field become halved.
-- Gadarla,
local SETCARD_ID_0 = 0xd3 --Kaiju
local COUNTER_ID_0 = 0x37 --Kaiju
local s, id, o = GetID()
function s.initial_effect(c)
	c:SetUniqueOnField(1, 0, aux.FilterBoolFunction(Card.IsSetCard, SETCARD_ID_0), LOCATION_MZONE)
	--special summon rule
	local e1 = Effect.CreateEffect(c)
	e1:SetType(EFFECT_TYPE_FIELD)
	e1:SetCode(EFFECT_SPSUMMON_PROC)
	e1:SetRange(LOCATION_HAND)
	e1:SetProperty(EFFECT_FLAG_UNCOPYABLE + EFFECT_FLAG_SPSUM_PARAM)
	e1:SetTargetRange(POS_FACEUP_ATTACK, 1)
	e1:SetCondition(s.spcon)
	e1:SetTarget(s.sptg)
	e1:SetOperation(s.spop)
	c:RegisterEffect(e1)
	local e2 = Effect.CreateEffect(c)
	e2:SetType(EFFECT_TYPE_FIELD)
	e2:SetCode(EFFECT_SPSUMMON_PROC)
	e2:SetRange(LOCATION_HAND)
	e2:SetProperty(EFFECT_FLAG_UNCOPYABLE + EFFECT_FLAG_SPSUM_PARAM)
	e2:SetTargetRange(POS_FACEUP_ATTACK, 0)
	e2:SetCondition(s.spcon2)
	c:RegisterEffect(e2)
	--Halve ATK
	local e3 = Effect.CreateEffect(c)
	e3:SetDescription(aux.Stringid(id, 0))
	e3:SetCategory(CATEGORY_ATKCHANGE + CATEGORY_DEFCHANGE)
	e3:SetType(EFFECT_TYPE_QUICK_O)
	e3:SetCode(EVENT_FREE_CHAIN)
	e3:SetRange(LOCATION_MZONE)
	e3:SetProperty(EFFECT_FLAG_DAMAGE_STEP)
	e3:SetHintTiming(TIMING_DAMAGE_STEP, TIMING_DAMAGE_STEP + TIMINGS_CHECK_MONSTER)
	e3:SetCountLimit(1)
	e3:SetCondition(aux.dscon)
	e3:SetCost(s.atkcost)
	e3:SetTarget(s.atktg)
	e3:SetOperation(s.atkop)
	c:RegisterEffect(e3)
end
function s.spfilter(c, tp)
	return c:IsReleasable(REASON_SPSUMMON) and Duel.GetMZoneCount(1 - tp, c, tp) > 0
end
function s.spcon(e, c)
	if c == nil then
		return true
	end
	local tp = c:GetControler()
	return Duel.IsExistingMatchingCard(s.spfilter, tp, 0, LOCATION_MZONE, 1, nil, tp)
end
function s.sptg(e, tp, eg, ep, ev, re, r, rp, chk, c)
	local g = Duel.GetMatchingGroup(s.spfilter, tp, 0, LOCATION_MZONE, nil, tp)
	Duel.Hint(HINT_SELECTMSG, tp, HINTMSG_RELEASE)
	local tc = g:SelectUnselect(nil, tp, false, true, 1, 1)
	if tc then
		e:SetLabelObject(tc)
		return true
	else
		return false
	end
end
function s.spop(e, tp, eg, ep, ev, re, r, rp, c)
	local g = e:GetLabelObject()
	Duel.Release(g, REASON_SPSUMMON)
end
function s.cfilter(c)
	return c:IsFaceup() and c:IsSetCard(SETCARD_ID_0)
end
function s.spcon2(e, c)
	if c == nil then
		return true
	end
	local tp = c:GetControler()
	return Duel.GetLocationCount(tp, LOCATION_MZONE) > 0 and Duel.IsExistingMatchingCard(s.cfilter, tp, 0, LOCATION_MZONE, 1, nil)
end
function s.atkcost(e, tp, eg, ep, ev, re, r, rp, chk)
	if chk == 0 then
		return Duel.IsCanRemoveCounter(tp, 1, 1, COUNTER_ID_0, 3, REASON_COST)
	end
	Duel.RemoveCounter(tp, 1, 1, COUNTER_ID_0, 3, REASON_COST)
end
function s.atktg(e, tp, eg, ep, ev, re, r, rp, chk)
	if chk == 0 then
		return Duel.IsExistingMatchingCard(Card.IsFaceup, tp, LOCATION_MZONE, LOCATION_MZONE, 1, e:GetHandler())
	end
end
function s.atkop(e, tp, eg, ep, ev, re, r, rp)
	local c = e:GetHandler()
	local tg = Duel.GetMatchingGroup(Card.IsFaceup, tp, LOCATION_MZONE, LOCATION_MZONE, aux.ExceptThisCard(e))
	local tc = tg:GetFirst()
	while tc do
		local atk = tc:GetAttack()
		local def = tc:GetDefense()
		local e1 = Effect.CreateEffect(c)
		e1:SetType(EFFECT_TYPE_SINGLE)
		e1:SetCode(EFFECT_SET_ATTACK_FINAL)
		e1:SetValue(math.ceil(atk / 2))
		e1:SetReset(RESET_EVENT + RESETS_STANDARD)
		tc:RegisterEffect(e1)
		local e2 = Effect.CreateEffect(c)
		e2:SetType(EFFECT_TYPE_SINGLE)
		e2:SetCode(EFFECT_SET_DEFENSE_FINAL)
		e2:SetValue(math.ceil(def / 2))
		e2:SetReset(RESET_EVENT + RESETS_STANDARD)
		tc:RegisterEffect(e2)
		tc = tg:GetNext()
	end
end

