This is my "Battleguard" deck. The "Battleguards" are not close to being a popular or even known deck type, but I tried to make something out of it to the best of my ability.
Obviously, the deck needs three copies of both "Swamp Battleguard" and "Lava Battleguard", since they are what gives the deck its name. On their own, they are rather uninteresting and even in pairs they only boost their stats by a small margin, but with "Feast of the Wild LV5", we can Special summon the duo for further Xyz and Link summons, or to go into their "boss monster" in form of "Battleguard King".
The "Star" series of cards provides some further summoning material, with "Tenma the Sky Star" being Normal summonable without tribute while you control an Earth monster (a requirement that the "Battleguards" can provide), while "Hayate the Earth Star" can enter the field via Normal Summon when a Light monster is present. They also bring their friends with the other Attribute with them when summoned, allowing for some swarming and the summon of "Kaiki the Unity Star", who then can summon the Fusion monster "Idaten the Conqueror Star" for a surprisingly helpful beater with an in-built search effect.
To make summoning some Level 5 monsters a little easier, I included both "Overlay Booster" and "Super Quantum Red Layer" into the mix, both sporting a Special summon effect and being overall useful for the strategy.
In the backrow you will find "Monster Reborn" for easy revival, "United We Stand" as a ghetto OTK option, "Raigeki" for board clear, "Pot of Desires" for draw power (we play enough copies of everything, so the banish effect is pretty much irrelevant), "The Monarchs Stormforth" as both removal and tribute summon option if needed and "Instant Fusion" to gain access to either "Invoked Raidjin" if you need an added effect on a Level 5 Warrior monster or "Giltia the D. Knight" if you could start a summon chain with "Hayate the Earth Star".
The Traps consist of "Lost Wind", which stops the opposing effect monsters while lowering their ATK to beatable levels, "Wall of Disruption" as a better version of "Mirror Force" in this deck since any damage you can inflict helps in the long run, "Crackdown" to steal the opposing defenses, "Battleguard Howling" for further damage and board control and a "Call of the Haunted" in case you need to revive another monster.
The Extra Deck is mainly Rank 5 Xyz monsters with useful effects, some Links to have certain options available, the "Instant Fusion" targets as well as "Idaten the Conqueror Star" and "Shura the Combat Star" for the "Kaiki the Unity Star" summon.
The deck is nowhere near consistent. In fact, it is very bricky and can have some serious issues in certain situations, but that is exactly why I listed it as a Casual deck. If you want the challenge of working with "Battleguards" though, this deck can be the way to go. I even made an archetype analysis for the "Battleguards" (as well as some other archetypes), which you can find here: https://cubiccreativity.wordpress.com/2020/08/20/archetype-analysis-battleguard/