Question

What are all of the possible shops for join avenue and what do they do>?

Answer 1

http://bulbapedia.bulbagarden.net/wiki/Join_Avenue#Shops
This should answer your question.

• Raffle Shop (win a prize each day)
• Beauty Salon (decreases EVs raising happiness)
• Dojo (increases EVs and level)
• Market (sells various items)
• Flower Shop (sells Berries and Mulch)
• Antique Shop (sells items that vary)
• Cafe (increases EVs, happiness, and level)
• Nursery (makes Eggs hatch faster)

Answer 2

Raffle:
>A Raffle Shop (Japanese: くじびきや Lottery Shop) provides a free, daily raffle as its only service, where the player wins a random prize. The chance of getting a greater prize increases with the rank of the shop.

Beauty Salon:
> A Beauty Salon (Japanese: びようしつ Beauty Parlor) offers various services increasing a Pokémon's friendship and lowering its effort values. If the chosen Pokémon is already at maximum friendship the Salon owner will decline to provide the requested service.

Nursery:
>Nurseries (Japanese: ほいくじょ Nursery) offer various services that make Eggs hatch faster.

Dojo:
>A Dojo (Japanese: どうじょう Dojo) offers various services increasing a Pokémon's effort values and level. A Pokémon will not evolve or learn new moves when its level is increased in this manner.

Antique Shop:
>An Antique Shop (Japanese: ふるどうぐや Secondhand Store) sells various unidentified items which are appraised by the shop owner after purchasing, granting the player a Hard Stone or a surprise item, such as an evolutionary stone.

Cafe:
>A Café (Japanese: カフェ Café) offers various services increasing a Pokémon's friendship, effort values, and level. A Pokémon will not evolve or learn new moves when its level is increased in this manner.

Florist:
>A Flower Shop (Japanese: はなや Florist) sells Berries and Mulch.

Market:
>A Market (Japanese: マーケット Market) sells various items, mainly in large batches at a discount. Some of these items are not sold in regular Poké Marts.

Source

Answer 3

So far, I've got:
Dream Shop: Lets you enter a raffle. First prize is a Master Ball.
Florist: Lets you buy Berries and Mulch.
Antique Store: Lets you find rare items (sometimes)
Barber: Ups your Pokemon's friendship but sometimes lowers some of their stats.
Deli: Ups your Pokemon's friendship.
Fitness Store: For a price, you can raise one of your Pokemon's stats, or even their level.
These are just the ones I've found so far. I'm not sure if there's more, since my Avenue is full.