Trashmolds.

[Toffee.]

Trashmold Magnum Explorer
EARTH / Level 3
[Fiend/Effect]
If this card is Special Summoned from the Graveyard OR flipped Face-up: Add to your Hand 1 "Trashmold" monster from your Deck. This effect of "Trashmold Magnum Explorer" can only be activated once per turn. Once per turn you can activate this effect: Discard 1 "Trashmold" card, and if you do, Draw 1 card. Then, Inflict 500 damage to your Opponent.
ATK 500 / DEF 1800

Trashmold Orbiter
EARTH / Level 1
[Fiend/Effect]
If this card is Special Summoned by the effect of a "Trashmold" monster, you can Tribute this card and Pay 1500 Life Points: Until the End Phase of this turn, the Opponent cannot activate cards or effects in response to the activation and/or effect(s) of "Trashmold" monsters.
ATK 700 / DEF 700

Trashmold Clawhammer Brigade
EARTH / Level 4
[Fiend/Effect]
As long as this card remains Face-up on the field, you cannot Special Summon non-"Trashmold" monsters. Once per turn, you can Target 1 Level 3 or lower "Trashmold" monster in your Graveyard: Special Summon the Target, and if you do, switch this card to Defense Position. This effect of "Trashmold Clawhammer Brigade" can only be activated once per turn. If this Attack Position card is destroyed as a result of battle: Special Summon 1 "Trashmold Clawhammer Brigade" from your Deck, and Decrease it's ATK by 1000.
ATK 1900 / DEF 0

Trashmold Drillrider
EARTH / Level 4
[Fiend/Effect]
As long as this card remains Face-up on the field, you cannot Special Summon non-"Trashmold" monsters. If this card is selected as an attack target, this card looses 1000 ATK during the damage step. If this card is destroyed by your Opponent's card(either by battle or card effect), Target 1 Level 3 or lower "Trashmold" monster in your Graveyard: Special Summon the Target. The following effect of "Trashmold Drillrider" can only be activated once per turn. During either player's turn, you can Banish this card from your Graveyard and Target 1 Face-up "Trashmold" monster you control: Target gains 800 ATK until the End Phase.
ATK 2200 / DEF 800

Trashmold Mammoth Armor
EARTH / Level 6
[Fiend/Effect]
During the End Phase of a turn in which 2 or more Face-up "Trashmold" monsters you control were destroyed by your Opponent's cards(either by battle or card effect), you can Special Summon this card(from your Hand). If this card is Summoned in this way, you can Target 1 card on the field: Banish it. If this card is destroyed by your Opponent's card(either by battle or card effect), you can Target 1 Level 4 or lower "Trashmold" monster in your Graveyard: Special Summon it. If this card declares an attack, it is switched to Defense Position at the end of the Damage Step. You can only control 1 "Trashmold Mammoth Armor".
ATK 2700 / DEF 1000

Trashmold Gigamound
EARTH / Level 6
[Fiend/Effect]
If a "Trashmold" monster you control destroys an Opponent's monster as a result of battle, you can Special Summon this card(from your Hand) in Face-up Defense Position. If this card is Summoned in this way, Draw 1 card. This card cannot be destroyed by card effects that do not Target it. If this card is destroyed as a result of battle: Add to your Hand 1 "Trashmold" Spell/Trap card from your Deck. You can only control 1 "Trashmold Gigamound".
ATK 2500 / DEF 1700

Trashmold Hercules
EARTH / Rank 6
[Fiend/Xyz/Effect]
2 Level 6 "Trashmold" monsters.
When this card is Xyz Summoned, you can Target 1 Defense Position monster on the field: Change it to Face-up Attack Position OR Destroy it and Inflict 1000 damage to it's controller. If you destroy a monster with this effect, then you cannot activate this effect of "Trashmold Hercules" for the rest of the turn. During the Battle Phase of either player's turn, you can Detach 2 Xyz Materials from this card: Negate the effects of all monsters currently Face-up on the Opponent's side of the field, and Decrease their ATK and DEF by 800.
ATK 2800 / DEF 2500

Trashmold Battle Hammer
Spell / Equip
Equip only to a "Trashmold" monster. Equipped monster gains 300 ATK. If the equipped monster would be destroyed by a card effect, destroy this card instead. If the equipped monster destroys an Opponent's monster as a result of battle: You can Special Summon 1 "Trashmold" monster from your Deck with a lower level then the equipped monster, in Face-up Defense Position. The monster Summoned by this effect cannot activate it's effect(s) this turn. You can only control 1 "Trashmold Battle Hammer".

Trashmold Swap
Spell / Quick-Play
Target 1 "Trashmold" monster you control: Change it's Battle Position. During the End Phase of a turn in which you activated this card, Draw 1 card.

Trashmold Junkyard
Spell / Field
You cannot Special Summon non-"Trashmold" monsters. Once per turn, if a "Trashmold" monster(s) is removed from the field by a card effect controlled by your Opponent: Draw 1 card. If this card is destroyed by your Opponent's card effect: Add to your Hand 1 "Trashmold" card, except "Trashmold Junkyard".

Trashmold Barrier
Trap / Continuous
All Face-up "Trashmold" monsters you control gain 200 ATK during your Battle Phase. If a Defense Position "Trashmold" monster you could would be destroyed as a result of battle: You can destroy this card instead. If this card is destroyed your Opponent's card effect: Draw 1 card.

Trashmold Bargain
Trap
Target 1 "Trashmold" monster you control, and up to 2 Spell/Trap cards on the field. Change the first Target to Defense Position, and if you do, send the other 2 Targets to the Graveyard. The Opponent Draws 1 card during the End Phase of a turn in which this effect was activated. You can only activate 1 "Trashmold Bargain" per turn.

Trashmold Construct
Trap
Target 1 Level 4 or lower "Trashmold" monster in your Graveyard: Special Summon the Target. Destroy it during the End Phase.

[Toffee.]

Decided to add to this.

[infinitysqrd]

Trashmold Drillrider seems a little counterintuitive compared to the other Trashmolds.

[Lonk]

I'm getting a Metal Shark Prayer vibe from this set.  Don't know if that was intentional.

 

Onto the topic at hand, this seems like a recursion beatdown concept if I am not mistaken?  Though, you mispelled "By" in the parenthesis on Mammoth Armor.  My only complaint that I would have is that the Deck seems like it would have difficulty getting past stall monsters (Spirit Reaper, Marshmallon, Grand Mole, ect.), so you might want to make something that would negate a battling monster's effects to help support the concept.

[Toffee.]

Tweaked Drill, and added an Xyz. Because why not.