[ Not yet approved by Lore Team]
The evolutionary line of the species Shelmet and Karrablast are quite unique and rarely observed in the wild. Due to my experience in both raising and documenting these species, I hope to create a somewhat comprehensive guide on how these Pokémon behave and can be put to human use.
Description and Behavior (Pre-Evolved)
Karrablast are bipedal bug type Pokémon, that are quite fierce for their small size. Their horn seems to mostly be used for offensive purposes, such as hunting prey.
Shelmet on the other hand, are built entirely for defense. Their soft body is protected by a strong shell which is coiled to create more surface area for the body to retract into. They seem to primarily be herbivores, showing little ability to hunt.
These two species are natural rivals. Karrablast have evolved the ability and instinctive knowledge to crack open the shell of a defending Shelmet. This does not always result in a successful hunt, however Karrablast have the best chance at using Shelmet as prey species compared to other predators.
Both of these evolutionary lines prefer humid environments. Shelmet in particular is at danger of drying out when there is no water nearby, although this is mitigated by its shell being able to store a certain amount of moisture. Since they are detritovores, feeding off of primarily dead or decaying plant mater, the swamp is a perfect home for them.
Karrablast similarly prefer the swamp or bog, sometimes venturing into more seasonal forests. They mainly follow their prey species, not really relying on humidity or other environmental factors. Their population size also directly scales with a select few species, mainly those of Shelmet.
Description and Behavior (Evolved)
The basic forms of these two species are nothing special all things considered. Both are relatively simple minded bug Pokémon that follow the simple rules of a prey/predator behavior.
However, their evolved forms are not only extremely rare, but also show completely different behavior than their base forms.
Escavalier evolves from Karrablast, gaining the shell-armor of Shelmet and going from a fierce predator to an opportunistic one, even going so far as to express scavenging behavior. This makes sense as their slower lifestyle requires less energy, and their considerable increase in power allows them to more easily break up and consume every part of a Pokémon, such as breaking bones to access marrow. While their diet has expanded considerably, now not only including other small bug Pokémon, but also Bird Pokémon or Lizard Pokémon, those living solitary still show a preference to hunting Shelmet, and even Accelgor.
Accelgor evolves from Shelmet, and goes through a similarly extreme change in behavior. With their shells missing, they are now at danger of drying out. They seem to get around this problem by creating a sort of bandage-like substance to cover their main body. This also gives them an immense increase in speed, now able to escape most, if not all predators. Due to this added agility, in addition to their ability to now learn many projectile attacks, such as Water-Shuriken, they are able to stay out of sight in almost all cases, making them vanishingly rare to spot. They also transition from pure herbivore to omnivory, as they are now able to hunt pokemon in a pinch, should other food be unavailable.
Both of these Pokémon now are fiercely territorial, showing an increase in intelligence as well as power or speed. If they find other members of their species they will most often try to hunt them out of their territory, only showing social behavior during mating.
Methods of Evolution
The most widely accepted way to evolve these two Pokémon is to trade them with each other. Though the exact process is unknown, much like other trade evolutions, it seems the electricity and exchange of information inside a trading machine stimulated the evolution process.
However in the wild, this method is not available, yet it is rarely possible to find these species in their evolved form. I have been able to construct a few theories based on sites I have found, though I have yet to observe the evolution of these Pokémon in the wild. I hope these theories can lay the foundation for further research:
Due to their natural relationship as Prey and Predator, as well as knowing the outcome of the Trade-Evolution method, we can assume that, if a Karrablast somehow manages to remove a Shelmet from its shell alive, and takes it for itself, it may result in evolution of one, or both parties. The fact that Accelgor are so rare in the wild may then stem from them usually dying during this process, however since they are so good at keeping hidden, this may be a falacy. More research is needed.
Keeping in the theory of electricity stimulating the evolutionary process of these Pokémon, i would propose that natural lightning may be able to induce evolution as well. Of course, this is not a hypothesis that is easy to test, and even with how rare the evolved forms of these Pokémon are, the chances of lightning striking two of them at the same time, and both surviving does seem like an almost impossibility. Still, i personally believe that electrical stimulation of some sort is the key.
While both Shelmet and Karrablast are on the lower end of the pokemon-intelligence spectrum, both are still capable of atypical behavior and problem solving. I have very rarely observed members of these species acting cooperatively, which is extremely out of the ordinary for what are normally prey and predator.
Shelmet can rarely be seen feeding on detritus while Karrablast protect it from other predators, and similarly Shelmet will help break down available Carrion with their acidic spit, to give Karrablast a way to feed without having to hunt. Whether this is a form of true interspecies cooperation, or simply the two Pokémon not currently engaging in a fight due to their natural needs being met is hard to say, more observation is needed.
I believe this kind of behavior, while unusual and rare, may be a deciding factor in the evolution process of the two Pokémon, as it brings them together for longer periods of time than simply one battle. However, it by itself does not generate any electricity or allow for the Karrablast to remove the Shelmet from its protective armor, and as such something else would need to trigger the evolution.
Common uses by trainers
Should these Pokémon be evolved through trade, they will show behavior mixed between what you would see after an evolution via battle, and one via cooperation. Thus they are a bit unpredictable to use alongside each other, and unless highly skilled trainers are available it is better to use them separately.
Excavalier can appear in a wide range of sizes, as it adapts to whatever shell it is given. This means that they make for ideal guards of both large and small spaces. Their low metabolism means they can stay without food or water for long stretches of time, and their territorial behavior means they will defend any given area very well.
Other uses for them include transportation of small amounts of valuable or fragile goods, as they are able to store things in their shell and fiercely protect them, as well as being quite useful in mining operations. Their brute strength can help with excavation of rock, although their lack of precision means they are unfit for archeological endeavors.
Accelgor is an excellent Pokémon to act as Guards. Their tendency to hide along with their speed means they will instantly notice intruders and be able to quickly warn anyone they are ordered to. Their ability to shoot projectiles, including a sticky glue-like substance, also means they can easily detain intruders by themselves from a safe distance.
Their propensity for drying out sadly means they are not fit to be used in many environments, however it gives them the unique advantage of being able to quickly traverse bodies of water, often faster than typical water type Pokémon.
Should a skilled trainer be available, or these Pokémon have been evolved via cooperation, they can also be used as an effective duo. I myself have used both to act as a warning system. Should a rampaging Pokémon appear, or the balance of an ecosphere be otherwise disturbed, their high intelligence means they can often act alone. Escavalier can easily defend against raging Pokémon, while Accelgor can use the distraction to restrain them.
I do however, not recommend these Pokémon to any aspiring trainers. They are somewhat hard to control, especially for younger children, due to their often instinctive behavior, not to mention their natural behavior towards the other species can lead to problems such as a captured, but still untrained Karrablast running off to hunt a wild Shelmet it saw. Not to mention that the effectiveness of these Pokémon in the standard battle format is not the best.
However should one be up to the challenge, raising them can be a very rewarding, especially if you manage to raise Shelmet and Karrablast together. You will find that their cooperative behavior can be trained, and make them extremely sociable and empathetic partners.