Hypeantonio, ¿podría estar Zygarde basado en la letra griega θ (theta)? Es que estuve mirando en internet qué podía significar Th y encontré esto:
In its archaic form, θ was written as a cross within a circle (A symbol of a cross within a circle or Another symbol of a cross within a circle), and later, as a line or point within a circle (The symbol of a line within a circle or The symbol of a point within a circle). In its archaic form (A symbol of a cross within a circle) theta is used as a symbol for Earth.
The lower-case letter θ is used as a symbol for:
A plane angle in geometry.
The potential temperature in meteorology.
The score of a test taker in item response theory.
Theta Type Replication: a type of bacterial DNA replication specific to circular chromosomes.
Threshold value of an artificial neuron.
A Bayer designation letter applied to a star in a constellation; usually the eighth star so labelled but not necessarily the eighth brightest as viewed from Earth.
The Watterson estimator for the population mutation rate in population genetics.
In ancient times, Tau was used as a symbol for life and/or resurrection, whereas the eighth letter of the Greek alphabet, theta, was considered the symbol of death.
According to Porphyry of Tyros, the Egyptians used an X within a circle as a symbol of the soul; having a value of nine, it was used as a symbol for Ennead. Johannes Lydus says that the Egyptians used a symbol for Kosmos in the form of theta, with a fiery circle representing the world, and a snake spanning the middle representing Agathos Daimon (literally: good spirit).[2]
The Egyptians also used the symbol of a point within a circle (The symbol of a point within a circle, the sun disc) to represent the sun, which might be a possible origin of its use as the Sun's astrological glyph.
Está en inglés (lo siento

), pero no lo encontré en español...