Question

Would Hidden Power Ground hit a Pokemon with Air Balloon?

Answer 1

No.

It's a ground type attack, so it will not. Plus I tested it, just in case.

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Source: tested it here
Hope I helped.

Comments

Ok  Thanks.

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1 fast question, where is the simulador for test moves like you did, the ''gold customgame'' ?

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Pokemon Showdown.
Is says gold custom game because I did it on a server called Gold and it was a custom game. :P

Answer 2

No it does not. Hidden power ground is a ground type move and will not affect the holder of the air balloon. Flying types will also go unaffected.

Hope I helped!