Inside the ruins there is a chart with a message on it. Base the letters off of that. They mostly look like the letters that they are though.
Chat with our AI personalities
they are Pokemon shaped like letters
if you catch all 28 unknown, including the exclamation mark and question mark unowns, the unowns will spell the alphabet and question & exclamation mark unowns i really dont know what they do.
Some Unowns
yes in solaceon
sealaceon ruins has unowns a-z!