Of course, Dialga also got its Primal Form; here it is.

Deviant artist tapwing created a menacing Primal Dialga Form. Dialga got a fiercer and cold-blooded look. Its body is surrounded by diamond shards and got a darker blue skin color. This form would be overpowered.
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References:
https://www.deviantart.com/tapwing/art/Primal-Dialga-556559147