With the exception of "Multiple Piece Golem", all "Piece Golems" have 0 DEF and average ATK for a monster of their Level. They also have an ascending/descending ATK and Level, with "Small Piece Golem" being Level 3 and "Big Piece Golem" being Level 5. "Medium Piece Golem" has exactly 500 more ATK than "Small Piece" and exactly 500 less of "Big Piece", with the latter having exactly 500 less than "Multiple Piece".
"Medium Piece Golem" and "Small Piece Golem" can Special Summon one another. If "Big Piece Golem" is on the field, "Medium Piece" can fuse with "Big Piece" to form "Multiple Piece Golem" which also has a built-in "De-Fusion"-like effect, allowing you to swarm the field if you Summoned it from your hand. "Big Piece" can also be Normal Summoned with no Tributes if your opponent controls a monster and you do not (similar to "Blackwing - Sirocco the Dawn"). The quickest way to use them would be to Special Summon "Big Piece", use its effect to bring out "Medium Piece" and then follow that up by using your new monster's effect to bring out "Small Piece" to boot. If you have a Fusion card such as "Polymerization" with you, use it as the final step to Summon "Multiple Piece" and use all four "Piece Golem" cards in one turn.
A "Piece Golem" Deck is mainly based around swarming and beat-down so it's important to use beat-down support cards that take advantage of swarming such as "United We Stand". Your main strategy with this Deck is to put as many Rock monsters (preferably "Piece Golems") into your grave and either use them with "Gaia Plate the Earth Giant" or cards such as "Call of the Haunted" and "Monster Reborn" to get their swarm effects quickly. Despite the fact that this Deck swarms, it does not Special Summon very much, so cards such as "Fossil Dyna Pachycephalo" will make a perfect addition since it is also a Rock and will be able to negate your opponent's Special Summons and even the game out.
Beware of cards such as "Thunder King Rai-Oh" and "Doomcaliber Knight". Both of these cards are often seen in a variety of decks and can prevent you from making your best moves. An easy way to prevent these cards from ruining the duel for you would be to include such as "Gaia Power" or "United We Stand" along with staples such as "Dark Hole". Even your "Big Piece Golem" can destroy these cards, making your Deck's combos available to you.