This just in!
Looks like the Seacons are being sold
either individually OR as
two-packs!
Turtler and Gulf are coming together as a 2-pack called "Transformers Generations Selects King Poseidon Wave 1 set (Seacons Turtler + Seacons Gulf)"
The two-pack is exclusive to TakaraTomy Mall (in Japan, that is), priced at 11,124 yen.
They are also being sold separately, with Seacons Turtler priced at 7,020 yen and Seacons Gulf at 4,104 yen, both still as TTM exclusives in Japan.
(Yes, "Seacons" plural instead of the singular "Seacon" for each of them because, in Japanese, the Seacons' team name is bizarrely always written in the plural form, contrary to how virtually every other subgroup name in Japan is always written in the singular form.)
There are also colored pics of the two figures, showing off all modes and configurations, confirming that Gulf can become his weapon mode (but the text notes that King Poseidon cannot hold the weapon with just one arm, suggesting that he may need to use both hands to hold it).
There's even an accompanying manga chapter that seems to go with the Star Convoy manga chapter, but also features Halfshell of the Beast Wars II Seacons.