I stumbled upon this illustration one day on pinterest and instantly fell in love. This is such a fun, great design and would potentially be a wonderful ad campaign for any of the brands featured. I love the apparent mix media, the watercolors with the ink splat and careful pen work. This may have been done with physical media but I would hazard a guess that it was done using illustrator and photoshop. Even if it wasn’t, this look is achievable using adobe software if a designer knows what they are doing.
I would start with line art done with a simple micron pen and then create some texture by painting watercolor on paper and scanning it in. I would put all of it in illustrator, then using the pen tool I would create the shapes and designs. I would arrange these in a pleasing fashion, then create some text or import a logo to arrange the designs around.