Soft & Wet's signature ability is to "steal something from [an object] and take it for itself", which works in conjunction with the bubbles. Josuke can thus steal aspects or properties of inanimate and living things. Said properties seem to also be smaller objects that come from a bigger object.

What can soft and wet steal?

Soft & Wet can steal sight, friction, etc. This ability was way too versatile and could be used in completely story-breaking ways, so Araki must of written it out. Look at the last arcs of Jojolion, and you'll see it.

What is soft and wet beyond?

After discovering the soap bubbles connection to Spin, Josuke unlocks the ability to control an invisible soap bubble known as Soft & Wet: Go Beyond. The invisible bubbles, formed with spinning lines, can pass through any object and erode it on contact.