Junkyard's basic servants are all mediocre but serviceable at a somewhat high cost. They are important because they generate Sol's Dragon Install resource.Some of Junkyard's elites are very strong and can make this tribe one of the strongest if they are used correctly.
210 Cost / 520 HP / 100 SPD / 10 RMC
Despite how little Drills do in a fight, Sol still needs to be using these to maintain map control.
Drills also gather Sol's unique resource (Gears) when attacking which Sol needs to activate Dragon Install.
When combined with Blockhead, it becomes buffed, gaining access to much stronger attacks but not by enough to make the Drills a good unit.
420 Cost / 800 HP / 75 SPD / 10 RMC
Blade's high cost and mediocre performance makes them a lower priority for Unlocking then Fire Wheel and Queen.
Blades generate gears at a faster rate and preform better in combat when compared to Drills so they are still useful to Unlock before or after Fire Wheel, Queen, and Sol's Abilities. The general case is to unlock them after your first Elite Servant if you are tied/winning but before if you are losing. That said Match ups determine heavily how much you use this Servant.
Next to Fire Wheel, Blade's are the best unit to pick up and drop off at the opponent's Masterghost should you have an opportunity for them to hit the Masterghost's shield uninterrupted. Can be enhanced by Blockhead to create a barrier around itself that is an active attack but this ability also will knockback some enemies making Blade's normal attacks whiff at times they normally wouldn't.
130 Cost / 370 HP / 90 SPD / 10 RMC
Pencil Guy is very fragile to the point where if an enemy Master is around they will one shot him. Because of this summoning other units takes priority.
Pencil Guy does have good DPS and the buff Blockhead provides strengthens the basic attacks with knockdown making them harder to approach though Blockhead also isn't worth summoning over Sol's better units, Sol's Abilities, and various items from the shop. If you are at a point where you have extra mana then there are still cases where you can add some much needed damage with this unit to your army so long as the enemy master isn't nearby. They can help you in pressing an advantage when paired with Blockhead because the enemy Master can't ignore the newly acquired knockdown effect on their attacks but they also can't ignore a Master vs Master fight if you force it.
340 Cost / 1500 HP / 115 SPD / 60 RMC
This is one of Sol's best units.
High attack power, long attack range, a stun effect, high movement speed, and knock back resistance make this Servant a problem for your enemies. While Sol can generally rely on Fire Wheel to cover areas he is not, you will find yourself wanting to keep an eye on this Servant so that he stays alive to gain EXP and levels. Fire Wheel alone can be a threat to the opponents Master Ghost as Sol can pick up and carry Fire Wheel to the Master Ghost, let Fire Wheel destroy the Master Ghost's Barrier, Then just use Overdrive or spam F8X, MC, repeat....
300 Cost / 1200 HP / 140 SPD / 60 RMC
Engulfer has a special ability to seal the enemy master's usable items and skills making him a solid Servant to pick up and carry with Sol as Backup for Master Vs Master encounters.
Engulfer isn't very good against other servants even if the enemy type is weak to mobile units so you generally go for releasing Engulfer after Queen and Fire Wheel.
480 Cost / 3000 HP / 40 normal (115 in mobile mode) SPD / 90 RMC
Gigant is a very situational Tank that has the unique gimmick of being able to change into different Servant types via 1 use items in Sol's shop.
The default Melee mode has a omnidirectional attack for defensive skirmishes (Melee mode keeps Armor type). The Armor mode has a large front facing charging AoE attack making it good for Offense. The Shooting Mode has a giant Lazer that is good at killing the enemy Master or Masterghost very quickly but the range is narrow and Gigant switches back to Melee mode after firing it once. Lastly Mobile mode increases Gigant's top move speed from 40 to 115 though it doesn't have any new special attacks with it. Each Transformation lasts 60 seconds.
Gigant can be a win condition if you get it to the enemy Masterghost however it is so slow and expensive that this is hard to do successfully. Gigant also is good at holding a front line for 1 of your lanes on the map making it good for maps with few chokepoints like Bel Canto Valley and Triora. If you want Gigant to move faster but cannot afford or don't want to use a Mobile Transformation Kit then it is possible for Sol to get behind Gigant and "push" it forward using Burst Dashes from Free Lock Mode.
Gigant is one of two units Sol cannot pick up.
320 Cost / 700 HP / 90 SPD / 60 RMC
Despite Blockhead's solid DPS, long range, and ability to buff every basic Servant type; he is often killed before he can make an impact.
The buff Blockhead gives to Drills and Blades isn't helpful enough to justify the cost, meanwhile the buff Blockhead gives Pencil Guy is very useful for Pencil Guy but both are low health Servants that won't let them live long enough to be effective for their cost. To top things off Blockhead is one of the units suffering from an EXP gain bug that prevents it from gaining experience points when attacking.
120 Cost / 780 HP / 350 SPD / 50 RMC
This is one of Sol's best units, especially for it's very cheap cost.
Queen has the fastest move speed of any Servant in the game and very high DPS. To offset her strength she has low health that is constantly draining but she is so cheap and impactful on the game state that she more than makes up for her downsides.
Queen excels at capturing ghosts and moving between them so quickly that she can change control of the map in a way no other Servant can. This allows for Sol to make explosive comebacks if the opponent leaves a lane of Ghosts unprotected.
Queen is very good at blowing through enemy groups so long as there are allies there to help keep her from taking damage.
It is a good idea to sell Queen before the end of a round to avoid paying the 50 mana maintenance cost. It is also a good idea to queue another Queen for creation as the round is ending so you have her ready sooner next round. Her basic attack does 42 damage 3 times and will destroy incoming projectiles while active. Her only other ability is a debuff that reduces nearby enemy attack by 25%.
There is an EXP bug with this Servant where it cannot gain EXP from attacking but this doesn't matter for Queen cause she's not going to live long enough to get levels anyways.
Queen is one of two units Sol cannot pick up.
120 Cost / 370 HP / 34 sec life
Sol has an ability he can purchase in his Organ to summon this minion. This is often recommended against purchasing as it falls of in value quickly and doesn't impact the game as much as other Skills Sol can buy.
This Minion does the job of adding an extra body to a fight which can potentially help in situations where you intercept the enemy Master between Ghosts with no Servants nearby. However a single Dispel will kill Hunchback and Sol doesn't have other units with threatening minion summons to bait a Dispel out so this skill is potentially useless against a good player. Even without the Dispel you are probably better off carrying a Servant with then dropping it and giving it the attack commandUp on D-pad by default if you want help in a fight.