I’ve seen arguments about whether or not Phione is a mythical pokemon or not, what are your thoughts on this?

This is a tricky topic, as it’s just as much of a debate within the research community as it is among trainers and the like. Nonetheless, I personally believe that because the only way a phione can come to be is through the mating of a mythical pokémon, this makes it mythical in a sense as well—just not, perhaps, by the strictest definitions. It’s essentially the equivalent of a demigod but a pokémon: admittedly not quite a legendary but certainly separate from a common pokémon.

Sinnoh Legendaries: Part III

Manaphy
The Seafaring Pokémon
Type: Water
Official Registration #: 490
Entry: According to Sinnoh lore, this small, sea angel-like pokémon is the legendary Prince of the Sea. Unlike other legendaries associated with the sea (specifically Kyogre and Lugia), it does not control the sea itself, nor does it control the storms above it or channels within it. Rather, its fantastic power—which it possesses at birth—allows it to bond with and communicate with all sea life, from the tiniest plankton to the massive, unfathomable creatures dwelling in the ocean’s darkest depths. Oftentimes, fans of legendary pokémon mock Manaphy and call it the most useless pokémon in a superhero fight, but let it be known that sea life includes both Kyogre and Lugia, so honestly, stop making fun of Waterman, comic book message boards on the internet.

Phione
The Sea Drifter Pokémon
Type: Water
Official Registration #: 489
Entry: According to Sinnoh lore, this small, sea angel-like pokémon is born from a Manaphy when mated with a ditto. How we know this—considering the fact that Manaphy is a mythical pokémon only rumored to exist and considering the fact that ditto are not native to the sea, never mind the other thousands of questions we have about phione—the author can’t say.