The only two breakable rocks in Victory Road are the thin grey rock and a large brown spiky rock. The spiky rock can only be broken by using Hyper Voice or Rock Slide on it, and it will give either a Hard Stone or a Float Stone. The thin rock can only be broken by using Surf, Muddy Water, or Water Spout on it, and it will yield a Damp Rock.
Hope I could help!
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