Saint Jean d'Aulps
There's not a great deal going on for freeriders in St Jean. Much of the area is covered with trees, which although make for a beautiful ski area, they don't leave much access to the un-groomed snow. There are two, more open areas that provide a little space for off-piste: Combe de Graydon and Col de Graydon. If you're dead set on powder you'll want to explore other areas of the Portes Du Soleil.
There's no freestyle scene to speak of in St Jean; no park. For this you'll need other areas of the Portes Do Soleil. Head to Ardent for quick access to freestyle terrain.
Looking on the St Jean piste map you'll see that the skiable area, Espace Roc d'Enfer, is split into two sections: Secteur Saint-Jean d'Aulps and Secteur La Chevrerie. As is common in the Portes Du Soleil, you have a few options for lift passes, depending on where you want to snowboard. If you want access to the full, local area, you need a Roc d'Enfer pass. If you're happy to stay on the St Jean side, there's a pass for this part only, with the boundary being Col de Graydon. If you have a full Portes Du Soleil pass, you can go anywhere.
The pistes are mainly suited to families and beginners/intermediates. The 20 runs or so are primarily reds and blues, with one or two beginner areas thrown in. Note there are some nice, long reds, if you like that type of thing. This corner of the Portes Du Soleil is undoubtedly quieter than the norm. You will find uncrowded slopes here. Those in the know sometimes use St Jean when the main resorts get busy.
The red, Follys, which runs from the Col des Follys peak back to the St Jean base station is a particularly picturesque descent. It's long, at around 5km, and without any lifts nearby it has a very natural feel, making its way down, through trees and close to the river at some points. If you have ventured to the Chevrerie side, this is the run that you must use to get back. It can get a little patchy near the bottom if the snow isn't great.
Uncrowded slopes are always a plus for beginners; more time and space to progress. The access to the green run area at St Jean is via a cable car, meaning beginners don't need to worry about a difficult home run to the bottom. Be aware that the higher areas at St Jean are reached using a pretty long drag lift, which isn't always a good thing for beginners.