I'm not actually gonna give him rather release form to balance it out plus I think I'm gonna keep his power level at a captains level for now also I've read over his abilities apparently I missed the part where He shift shapes but aside from that I'll post his abilities here and get your thoughts on it, the last thing I want to is create an over power character which is why my shikai and bankai are usually so weak.
Sorry if this doesn't make sense is some areas I got this from the wiki
And plus it might be describing his attacks from a game.
Shapeshifting: Arturo has often been portrayed as a shapeshifter in the storyline, having taken on the forms of several characters; including Yoruichi Shihōin, Shinigami and Zanpakutō spirits alike in order to manipulate other characters in the story to achieve his ends.
X-Shaped Projectiles
X-Shaped Projectiles: Arturo has the ability to fire X-shaped projectiles. The blast seems to manifest a short distance in front of him, apparently summoned from above him and not from his own being.
Sonído: Arturo has also shown that he can use Sonído effectively in combat. He can even use it to perform combination attacks on his opponents.
Beam Saber
Beam Saber: As a substitution for actually using his Zanpakutō in battle, Arturo can manifest a powerful, dark colored saber of energy that materializes when his fingers extend forward. The saber produces lightsaber-like sounds when swung. It is very strong, similar to a Shinigami's Shikai.
Beam Saber Assault: Arturo can use a technique with his beam saber when he gets close enough to the opponent. He extends his blade, and proceeds to attack the opponent relentlessly while using Sonidó, overwhelming them. He gets a total of sixteen hits, followed by a 17th that knocks the opponent forward. Arturo begins the attack shouting, "DANCE!" and ends it with, "DIE!", while stabbing the opponent in midair. Afterwards you can hear him say " I've grown bored of your face."
Spatial Prison: A unique and apparently more battle-oriented version of the Negación technique used by Menos Grande. Arturo can summon a powerful circular shaped spatial prison that temporarily paralyzes targets absolutely. In contrast to the white Caja Negación used by the Espada, it is black.
Immense Spiritual Power: It is noted several times that Arturo has an overwhelming amount of spiritual pressure, exceeding that of Captain-level. His presence can be felt from a very long distance. He is so powerful that the need of a Reiryoku-absorbing item that could potentially kill the user was necessary.[2]
Arturo's Cero
Cero: Arturo uses a massive version of the Cero that inflicts major damage. It is still red in coloration, but it is far bigger, and has proportional strength to its size. But in the game Bleach: The 3rd Phantom, his Cero is shown to be white in color. [3]
Gran Rey Cero: In addition to his already powerful Cero, Arturo is also capable of using the Gran Rey Cero, a particularly strong version of Cero which is usually exclusive to the Espada.[2]
Zanpakutō
Arturo's Zanpakutō is called Fénix (不滅王 (フェニーチェ), Fenīche; Spanish for "Phoenix", Japanese for "Immortal King") (Fenice in the English version)[2]; its release command is unknown. In its sealed form, Fénix resembles a basic katana with an hourglass-shaped guard. Arturo apparently opts not to use the actual sword, instead relying on an energy blade he projects from his hand.
X-Shaped Projectile: Much like his unarmed version, Arturo can summon a powerful X-shaped blast with his Zanpakutō. This variant seems to be more powerful than his unarmed version. [2]
Power Absorption: Arturo's Zanpakutō has the power to absorb the spiritual energy of those it defeats, adding to its wielder's strength.[2]
Wings
Arturo's Green Wings
Arturo has two different sets of energy wings: the first, which constantly are on his back throughout gameplay, are two green wings which look similar to the single wing Uryū Ishida grows when he enters the Quincy: Letzt Stil.
Arturo's Red Wings
The second set of wings, which appear during his ultimate attack mode, are made of multi-colored flames. Arturo gains a huge increase in power, primarily in his Reiryoku and Reiatsu, which is the equivalent of an Arrancar releasing their Zanpakutō.