While lacking in terms of attack, this deck offers many forms of card removal through the effects of it's fusion monsters. Monsters in this deck can also protect and give additional effects to each other by union equip.
Equipping union monsters is a big part of this deck's strategy. The monster that is equipped with a union monster gains protection from being destroyed, by destroying the union monster instead, and also gains additional effects based on the union monster equipped. Use Roll Out! to equip a union monster from your graveyard to an appropriate monster on the field.(Take note that a monster can only equip one union monster at a time.)
I usually run just one Luminous Spark and one Machine Assembly Line while I run 3 Frontline Bases. Having extra Continuous spells is good ammo for the fusions and with Roll Out!, if I sent B-Buster Drake as ammo for an effect, I can chain it to bring Drake back as a Spell protection shield
What to change:
Max out Extra Deck
+2 B-Buster Drake
I recommend running 3 Buster Drakes and at least two Roll Out! and two Union Scrambles. I've gotten so many swarming OTKs from those two cards alone. Plus Union Scramble's graveyard effect can replenish any XYZ fusions' effects for one extra measure
Man, wish we had ABC instead. Banishing stuff is way better.
I've been toying with this deck a lot recently. I think Heavy Mech Support Armor is not that good, and instead I use Heavy Mech Support Platform. This is because this deck generally lacks in the ATK stat. For this reason, I'm using only 2 Frontline Bases and 3 Roll Outs, since reviving Union monsters that buff the ATK of your monsters is so valuable. Roll out is the real MVP of this deck imo.
Also, I use Sleight of Hand as a skill, since it helps you get that much needed ATK, plus it gives something to discard if you have something to target with your fusions.
Also, no Enemy Controllers, use Sphere Kuribohs instead if you have them.
XYZ summons applies to VWXYZ monsters, as per listed above, those monsters can be Special summoned from your extra deck without using polymerization (very similar to Contact Fusion except the monster stays on field), that is why this is commonly referred to as XYZ summons.
De-Fusion can be activated targeting a fusion monster on the field. So if all fusion material monsters from that targeted fusion monster are in the GY from De-Fusion's owner, all of them can be special summoned. This second part of the effect is an optional effect, so you can activate a De-Fusion targeting a Fusion Monster even if its materials aren't in your GY.
I added gravity blaster and got my z metal tank to 10000 damage
Considering XZ is able to remove face-down backrow card, and another union monster adds 500 ATK DEF and extra life for the tanks, I guess sergeant electro and RMM are not that significant changes... if consider union interactability, I'd prefer the machines
Ectoplasmer destroys both monster and union... Is this a glitch?
I am a fan of the principle of the union deck. You'll find that your backrow is always clogged. Without having 5 zones, this deck is weakened severely. With 5 zones, you could keep each monster protected from destruction 2-3 times a turn. With just 3, it becomes tough to not have a full backrow. Great draw speed. Great revival. Great card removal. Solid Attack. (X-canon plus union can get you a 2200-2400 monster turn 1) The only downside is a clogged field. Which always happens since you don't win in a couple turns.
for this reason I would limit the number of continuous spells in this deck from 4 to 2, and include a sphere kuriboh (or two) for defense. also, roll out seems decent but there are probably better cards for defending your union monsters (windstorm, mirror wall, enemy controller)