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Dragalisk is also obtainable through the same script but he's not in the regional dex (dex number ??? and you can't see him in either the normal or the Xenodex). Ground/Ice
Sent out into battle, he appears in the form of a Ditto. Stats are the same, moves are the same, ability still activates.
It appears like the devs have no plans to make Dragalisk catchable or they still hadn't worked out how to portray his huge size in battle format so left his sprites for an update later