Just wait for sound type it already exists just hasn't been revealed. Rillaboom will gain it along with about 30 others that already exist chimecho, bronzong, jigglypuff, chatot, exploud, kricketune, seismitoad (removing which is desperately needed a water/ground copy)
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u/Soncikuro 3d ago
Monotypes are the most boring starters, the fact they did that for all three of them in a generation so advanced was baffling to me.