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 Golem" and exactly 500 less of "Big Piece Golem", with "Big Piece Golem" having exactly 500 less than "Multiple Piece Golem".
"Medium Piece Golem" and "Small Piece Golem" can Special Summon one another. If "Big Piece Golem" is on the field, "Medium Piece Golem" can fuse with "Big Piece Golem" 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 Golem" 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 Golem", use its effect to bring out "Medium Piece Golem" and then follow that up by using your new monster's effect to bring out "Small Piece Golem" to boot. If you have a Fusion card such as "Polymerization" with you, use it as the final step to summon "Multiple Piece Golem" 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-type 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.