{Apologies for the long delay between chapters, I got a new job that's been draining my energy for writing.}
Overview-
Whether seen floating on the surface of the ocean on nights with a full moon or buried in the sands of an ocean trench, Starmie are a sight to behold. These starfish pokemon are found throughout the world's ocean, able to live anywhere. Breeding can only occur in areas of warmer temperatures however, so the Arctic oceans do not contain any Staryu. Starmie are very often seen in competitive battling circuits, able to shoot around the battlefield and send barrages of strong elemental attacks at their enemy. Their fast regenerative capabilities allows them to take more blows then one would expect of a starfish only 4 feet tall.
Starmie do not have the standard five senses, with touch being the only comparable sense shared with humans. Starmie understand the world around them through the Psychic Sense and aquakinesis. By releasing a subtle pulse of psychic energy from their core in a manner similar to echolocation they gain a very thorough understanding of their environment. While all Psychic types are capable of this Starmie are one of the species that have a specialty in the technique, with most Starmie being capable of passively detecting their surroundings without consciously sending out a pulse. Combined with their aquakinesis Starmie have a perfect sense of their surroundings in their sea habitat.
Starmie have very strange biology, even for a marine pokemon. With a core more similar to a Rock type's biology, profound psychic potential on evolution, and a reproduction system somehow tied to starlight the pokemon has stumped marine biologists for centuries. The starfish have a lifespan of around 91 years, growing in size over the course of their life. Wailord song seems to have a negative effect on Starmie, causing their cores to start flickering between colours rapidly and the pokemon to form psychic barriers around them to block out the sound.
Starmie's core is the only truly vital organ the pokemon has. The gem acts as the starfish pokemon's brain. The organ is more comparable to an inorganic rock type organ than any other water type organ, somehow growing extremely complex circuitries of internal flaws and facets able of storing information as effectively as neurons. Psychic energy flows through these circuit patterns, forming the mind of the Starmie or Staryu. The outer layers of the core are solid silicon, protecting the more fragile internal layers making up the mind. The limbs are connected to the core though five or ten, depending on evolution, branching prisms extending from the core through the center of the limbs.
Lifecycle-
Staryu hatch in warm shallow waters in groups of eggs numbering between one-ten thousand per group. Measuring in at one millimeter, they ride the ocean currents wherever it takes them. Their core is completely transparent and very rudimentary. Their diet consists of plankton smaller than they are at this stage, and there are theories that they somehow siphon energy from starlight in order to grow. Staryu will gradually grow in size over the course of 10 years until they reach the size most people associate with the species, two and half feet tall. The vast majority of Staryu will die before reaching this size, consumed before they can defend themselves. Throughout the years their core will darken in hue, going from clear as glass to a bright red comparable to rose. Around the core a band of fortified calcium plates grow, protecting the Staryu's only vital organ while allowing a portion to remain exposed.
Once they have grown large enough Staryu will begin learning how to harness their psychic energy. They will begin using weak psychic techniques such as Confusion alongside aquakinesis to form a constant current of water to pass through their limbs, consuming the plankton before cycling it back to the larger ocean. Staryu that have grown to the species standard are preyed upon by much less pokemon, Carvanha and other Dark types being their main predators. The only defense Staryu have against such pokemon is flashing bright colours from their core in the hope of disorienting the predator. Against other pokemon they use psychic techniques in conjunction to guarantee their success.
After a Staryu has lived for 17 years it will begin preparing for evolution. Floating to the surface it will expose its core to starlight, gathering the strange energy for months. It will follow the ocean currents out to deep water, filling its core with as much starlight as it can as it drifts out. This journey usually takes a month or two, fraught with danger as it is exposed to passing predatory flying types. If it survives it will pass over an ocean trench at some point, where it will begin sinking. As it sinks lower and lower it will begin using the gathered starlight to manually recut and facet its core, changing a relatively simple circuit into an extremely complicated network of facets and flaws. Ocean trenches are hotspots of usable aura, taken in to reinforce the most vital channels of the core as the protective layers are stripped away and changed. This process will take days, crafting each channel individually to perfection. Once the Staryu is finished it will cycle the psychic energy forming its mind into the improved core, triggering its evolution. The pokemon will reform an even stronger layer of protective minerals over its core, alongside doubling its number of limbs.
The newly evolved Starmie will live its next few years in the ocean trench where it evolved, attuning itself to its newfound capabilities. Its psychic potential will match an Alakazam's, taking in an extreme amount of environmental information every second. Its Aquakenisis will grow in strength as well, able to puncture steel plating with relative ease. Starmie remain filter feeders, forming currents that weave between all of their limbs to feed. After it has regained a level of control of its strength it will rise to the surface. Starmie are capable of communicating with each other over vast distances through flashing out specific patterns of starlight from their core. Through such communication the starfish gather into groups called constellations that number between 7-13 members. The Gem sea is rife with such constellations, to the point that on many nights it is difficult to tell where the sea starts and the sky ends.
Reproduction-
Starmie reproduce through spawning. The pokemon are hermaphroditic, able to produce both male and female gametes. Each constellation of Starmie seems to run on their own schedule in regards to breeding, linked to a particular constellation in the sky. As such, they tend to breed yearly when their linked stars are at their peak. Each Starmie will release their gamete into the water and flash bright colours from their core, sending signals out into space. After each member has finished signaling the constellation will use their aquakinesis and psychic powers to form currents to spread the gametes out onto currents leading to shallow water. During this process the gametes will mix and form thousands of miniscule eggs.
Starmie are capable of immense regenerate feats as long as their core remains whole. In extremely rare circumstances they can make use of these capabilities to reproduce alone. By carefully using their psychic abilities to split off a limb the Starmie can fashion a Staryu body around a suitable gem as a core. Clamperl pearls, Moon Stones, Eviolite and even fragments of a broken Staryu or Starmie core are all able to act as a core. The Starmie forms channels in the core and grows its split limb into the right shape around it until it has fully integrated, where it then fills the core with starlight and psychic energy to form a new mind. The resulting Staryu is just as capable as a naturally born one, with no notable changes. The colour of their core and body is the only significant change, having a light cyan body and blue hued core.
Misc.-
Starmie and Gyarados are the heraldic pokemon of the historic Cerulean city noble line. Representing strength and adaptability, it was customary for the Lord or Lady of Cerulean to have at least one of them as their companion pokemon. The last Lord of Cerulean before its unification with the newly formed Indigo nation had both as his companions. In the battles preceding his defeat at the hand of the first Campion his Starmie was struck by a fatal blow to its core. The shattered pieces were gathered, with the majority scattered to the sea as was the funeral custom of the time. Seven pieces were kept and fashioned into jewelry alongside ceruleans and sapphires, coming to be known as the Star's Tears. Over the centuries the set has been passed down, eventually entwining themselves with the position of Gym Leader in Cerulean city. They are now in the hands of the Waterflower sisters until they are passed down to the next generation of Leader.
While wild Staryu will go through a months long journey in order to evolve, it is not the only way they can evolve. Water Stones are formed of the right frequency of aura needed, able to be drawn upon to reinforce vital channels in the same way. Using a Water Stone a Staryu can evolve anywhere as long as they have enough starlight to complete the process. It is recommended that any captured Staryu be brought to a Pokecenter to evolve, as the medical professions there know exactly what to do in order to keep the pokemon safe throughout the process. There has even been one recorded case of a Staryu evolving without either, using only the aura of its own body. The Staryu in question was over 30 years old at the time and was unable to migrate to the greater ocean.
Trained Starmie are incredible in both battle and contest. Each of their ten arms is capable of channeling moves, along with the face of their core. Through training they are capable of shooting out barrages of eleven moves at once, overwhelming even the toughest of natural defences. Their crystalline core is able to handle learning TMs very easily, only needing a couple of hours of rest between each disc. This makes them a very common sight in battling tournaments, as the level of effort to teach them a new move is much lower than most pokemon. They still must spend time training in order to master their learned moves however, as no amount of bizarre biology can match the mastery only able to be earned with time.