Gameplay-wise, I think her role should involve "management". By this, I mean that she could have multiple variations of attacks (think Peach's F-smash) and that she can cycle through them. She'd have moves for many situations, to suit her customer's needs (i.e. beat the crap out of them). She can also have an attack that's extremely weak initially, but gets stronger the more it lands; it'd be the only attack in-game that ignores stale-move negation. I dub that move "sales pitch" (advertisement); something you literally need to spam to make it stronger. That move would be her bread and butter: you will live and die by the sales pitch. Moreover, she'd also have a move or two with limited usage à la Robin's tomes; in-game it would be known as budget (or maybe inventory?). Overall, I imagine her being very versatile, but also complex.
With that in mind, here's examples of what I'm talking about:
Side special: Perfume cloud. Uncharged does small damage. Similar to Piranha Plant's poison, but smaller radius. However, when fully charged, it heals whoever is in range instead of dealing damage.
Foward-Smash: Cycles between a pair of scissors that deals more damage at the tip, a clutch bag that has shorter range but super armor when charged, or a hanger that works like a boomerang projectile but is very punishable.
Neutral special: Wardrobe. Press B to cycle through clothes that function like different projectiles. Think Pacman's fruit. Uncharged you throw a shoe - the ultimate disrespect. Hold it a little longer for more clothing/accessories to make it a multi-hitting attack (think Ridley's fireballs but clothing and wackier physics). When fully charged, you end up throwing an entire outfit that deals decent damage and flies in multiple directions. Stylish. Can be powered up further with Down special.
Down special: Sales pitch (advertisement). She holds up a magazine or something and says things like "Try it on..." and "Take a look!" She'll say things more enthusiastically and the dialogue will get zanier each time it hits. Deals very little damage initially but gets stronger the more it lands. Also powers up neutral special and replenishes budget/inventory.
Pummel: Hits opponent's face with a sponge and starts applying makeup on it. The longer you pummel, the more makeup gets smeared on them. The visual change is purely cosmetic and gradually disappears over time.
Forward-air: Microphone swing. It doubles as a tether recovery.
I imagine her tilts being powerful items (things like store furniture and a cellphone that stuns, for example), but only for a limited number of uses. Remember, she's fighting on a budget (her inventory is finite), so when it runs out, she resorts to weaker attacks like slaps, dance moves, model poses, etc.
The general idea is to force opponents to approach you by using the healing perfume and throwing clothing at them. Then advertise once they're in range. Conversely, you can fight up close with items from your boutique (including furniture!), and when all else fails, you rely on your smarts, stylish dancing, and glam-to-glam hand-to-hand combat. Obviously, her walking animation is going to be a catwalk strut.