Going Nuts

Other than the various Synchrons and Warrior-named Warriors, Yusei mostly uses low-Level Machine-type monsters in his Deck. Just to avoid being too obvious, he also uses some random monsters deemed "warriors" and some chickens too.

Let's start with Healing Wave Generator:

Once per turn, you can select another face-up monster  you control  to gain Life Points equal to that monster's  Level x 100.

Generator has an Ignition Effect. It targets, and its target must be face-up when it resolves. Nothing too surprising.

Then, we have Quillbolt Hedgehog:

If you control  a face-up  Tuner monster, you can Special Summon this card from your Graveyard. If this card was Summoned this way, remove it from play when it is removed from the field.

Hedgehog has an Ignition Effect. In order to Special Summon it, you must control at least 1 Tuner monster when the effect resolves. When it succeeds, it will set a Condition on itself that will Remove it from Play when it leaves the Field. Flipping Hedgehog face-down removes this Condition. If Imperial Iron Wall is active, Hedgehog is sent to the Graveyard. Note that there is no limit to how many times you can activate Hedgehog, so if Light and Darkness Dragon negates the activation of this effect, you can simply activate it again. Similarly, if Iron Wall is active, you can activate its effect again, as it will be sent to the Graveyard instead of being Removed from Play.

Other Machines are the "vehiclers" monsters. Unicycular is a Normal Monster, and the other two, Bicular and Tricular, work exactly the same:

When this card is destroyed by battle, you can Special Summon 1 "Unicycular" from your hand  or Deck.

When this card is destroyed by battle and sent to the Graveyard, you can Special Summon 1 "Bicular" from your hand  or Deck.

Both vehiclers are your average recruiters: Optional Trigger Effects, activated at the End of the Damage Step. The key difference between each other is the Bicular activates if destroyed in battle and Removed from Play while Tricular must go to the Graveyard.

The next Machine is Turbo Booster:

If you have Normal Summoned a monster  this turn, you can Special Summon this card from your hand. You can Tribute  this card to destroy 1 monster  your opponent controls that battled one of your monsters  this turn.

Turbo Booster has a Summoning Condition, and an Ignition Effect. The Summoning Condition is an Inherent Special Summon that you can only perform during your Main Phases. The Ignition Effect tributes Booster as a cost, and targets 1 monster. This effect can only be activated during your Main Phase 2 (in order to be able to determine which monsters have battled this turn). Remember that in order to "battle", monsters have to go through Damage Calculation, so the opponent's monster must have battled with yours and survived this Sub-Step.

There are still more Machines. Let's look at Tuningware:

If this card is used for a Synchro Summon, you can treat it as a Level 2 monster. If this card is sent to the Graveyard  for a Synchro Summon, draw 1 card.

Tuningware has two effects. The first effect is a Continuous Effect that you can apply while Tuningware is face-up on the Field. If Tuningware has its effects negated, such as if it was Summoned by Junk Synchron, this effect cannot be applied. The second effect is a Mandatory Trigger Effect that you activate upon the successful Synchro Summon of the Synchro Monster. Being mandatory, it will cause you to lose the Duel if you have no Cards in your Deck.

The last Machine-type monster is a very small Synchro: Armory Arm:

1 Tuner + 1 or more non-Tuner monsters
Once per turn, you can equip this card to a monster OR unequip it to Special Summon this card in face-up Attack Position. While equipped to a monster by this effect, that monster gains 1000 ATK. When the equipped monster destroys a monster by battle and sends it to the Graveyard, inflict damage to your opponent equal to the destroyed monster's ATK.

The first thing to notice is that, despite having similar effects to a Union Monster, Armory Arm is not a Union, so you can't target it with Formation Union, but you can equip it to a monster that already has a Union. The first effect is an Ignition Effect that targets, and unequipping is an Ignition-like effect of a Spell Card, much like Unions. The ATK bonus is a Continuous effect, of the Equip Spell Card, of course. The last effect is a Mandatory Trigger-like effect (Spell Card) that activates at the End of the Damage Step. Armory Arm and its target must be face-up in order for the effect to resolve properly. Regardless of who owns the equipped monster, Armory Arm inflicts damage to whoever is the opponent of Armory Arm. That is to say, the player that doesn't have Armory Arm in his/her S/T Zone.

That covers some more Yusei monsters, but there are still a few more. If you have any questions, feel free to drop me an e-mail at ness00[at]gmail[dot]com.