Starting from the Adil Su valley base camp, you first better ask the person in charge about the crevasse situation on the approach route to Gumachi. Don't forget to mention you want to climb the peak from the SW and not along the normal route.
There are two ways to get to the foot of the peak:
Along the sandy ridge (1) to the glaciers or down into the main valley (2) and then onto the glaciers.
1) Walk out of camp and stay very close to the big rocky and grassy peak on you right. Continue on the path over the meadows until you hit a narrow and sandy rigde.
The ridge can be a bit scary if there have been recent rains and you better be very careful about loose gravel. At the end of the sandy ridge, walk slightly to your left onto the glaciers. This is to avoid steeper snow and ice later on and also to paly it safe concerning falling rocks, ice and debris from the lower reaches of Djan Tugan.
When Your'e in the middle of the valley this route joins 2.
2) Leave camp down to the middle of the valley and the river at the bottom of it. Continue up along the river until you hit the glaciers. The situation here changes from year to year, but it's an easy walk on the glaciers until you hit the place where 1 joins. Needless to say, don't walk on top of the snow where the river flows underneath.
Walk on the glacier towards a little peak in front of you. It's called Pik Skaliye. When you see a steeper slope on your left, head for it and climb it. Some climbers use ropes here because of the potential crevasse danger, which I personally think is minimal on this 30-35 degree slope. There is a big crevasse in front of when on the little plateau after the slope. It's easy to avoid, walking along it until it closes further to your left. A steep section takes you to the 2B (Russian Pass Rating) at 3580m. you're now at the foot of Gumachi and Aristova.
On the rocky section underneath the summit
Walk along some rocky sections and enter the snowfields on your right. Beware of the ridge on your left as there are lots of loose rocks here and the drop to the glacier is probably fatal. When at the bottom of the snowy slope leading up to Opmumalniye Pass (2B), try to climb as much to your left as possible as the slope is slightly less steep there.
The slope probably have a maximum of 35 degrees.
When on the pass at 3780m you have to walk towards your left to climb Gumachi.
Watch out for the ridge as it's heavily corniched!
Stay below the edge of it!
The best way up the rock face is to stay below its highest ridge, i.e. hold left until you find an obvious passage up to where the ridge ends. The summit of Gumachi is not far off and some minutes of easy scrambling on big rocks takes you ro the pole that marks the summit.
A sketch of some of the routes in the area.
Crampons, walking sticks or a long ice ax.
It's a long way on snow and ice, so be sure you have boots you don't get cold in. A rope and harness could be an idea for careful mountaineers, especially if you want to traverse Gumachi and walk down on the long and quite precarious ridge on the other side.
Beware of crevasses on the approach!
If you want to attempt Aristova at the same time, you have to bring a rope and possibly also a couple of pitons/cams/nuts for the tricky sections on the ridge. There may be nasty corniche building here.