Gen 3 Mysterious Offset 10

[Metropolis]

Bulbapedia claims the two bytes at offset 9 and 10 represent the Pokemon's language:

Note these are listed in reverse order byte10 followed by byte 9 due to little endian format.

Hex Language

0x0201 Japan Flag.png Japanese

0x0202 England Flag.png English

0x0203 France Flag.png French

0x0204 Italy Flag.png Italian

0x0205 Germany Flag.png German

0x0206 South Korea Flag.png Korean

0x0207 Spain Flag.png Spanish

Actually it is only byte 9 that represents language. A Lapras egg I bred using a Lapras and Ditto had 01 as byte 9 and 06 as byte 10, which changed to 02 as byte 9 and 02 as byte 10 upon hatching. The nickname is Japanese for eggs, so it's understandable the language would begin as Japanese.

I think only byte 9 is language and byte 10 has a different purpose relating to eggs. I'm going to try breeding different species and see if it appears differently for a Pokemon that hatches slower than lapras.

So far a Charmander egg and Weedle egg have had the same 0x06 and 0x01 combination. I can't deduce any more than:

0x02 = Not egg

0x06 = Egg

Perhaps it relates to sprite, ie whether to draw the Pokemon with the egg sprite. All this was in FireRed. It's worth testing changing this value for Pokemon without the egg flag amongst the IDs. Since Pokerus is stored twice (one inside and once outside the encrpyted block) it's possible this is the same here and it's just so the game can load the sprite without having to decrypt the blocks.

Amazing 10 years later there's till mysteries in these games!