The Meadow and Marine patterns are so far the only patterns available natively in the game. Presumably, they'll inevitably release events for other patterns, as they've done for previous games.
As you'd expect, the game already has data and Pokédex entries for the remaining forms, which can be seen by hacking them in:
And to clarify, the Spewpa you get from the Lumiose Museum is the only way to obtain the Marine Pattern right now.
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