For the least technical approaches to this route, use Approach 1 or Approach 2A on the Main Page. From 7,882-ft Sheep Lake it will be necessary to boulder hop and talus and scree slide 1,000 ft up to the 8,840+ ft saddle between He Devil and She Devil. There are no issues except the state of the blisters on your feet. Also, the route can be approached by way of She Devil (Approach 2B) but there's more Class 3.
From the 8,840+ ft saddle between He Devil and She Devil, the idea is to climb up near the crest of the ridge on a series of ramps trending left and right. These ramps intersect such that you can generally keep scrambling up.
Eventually, it will be necessary to scramble up a short, 30-ft Class-4 chimney but it's not really hard (good holds and stemming).
Above the chimney, more scrambling on the south side for about 100 feet leads to more ledges. At some point (maybe 200 ft from the chimney), the route crosses over to the north side of the ridge and follows a broad ledge to an end at a slabby area intercut by shallow gullies and indentations.
Climb up and across the slabs aiming for the obvious notch at the head of the gully (trees in the notch). From the notch, cross about 100 feet on the south side again to a point where a gully leads right. You can take the gully or continue straight (west) around a small buttress. The gully completion finishes on the north side of the summit (the cairned summit). The straight (westward) completion ends at the South Ridge in trees closely below the summit. Scramble up boulders and sand to the summit.
Two Highpoints and the South Peak
There are two summit points of equal height within a hundred yards of each other on He Devil. They are separated by a depression with an interesting rock fin in it. The rock fin makes for a fun Class-4 scramble for those looking for some adventure. The fin can be circumvented, though (Class 3). For true peakbaggers, both summit highpoints should be visited.
In addition, He Devil's South Peak (9,280+ ft) is a quarter-mile away. Descend from the summit along the South Ridge. A little bit of Class 3+ downclimbing gets one to the notch, after which simple Class 3 scrambling gains the South Peak's top.
A short rappel or downclimb from the notch before the South Peak summit gets one down to ledges on the SE side of the Main Peak. With a little routefinding skill, one can traverse ledges back to the 8,840+ ft saddle at the base of the East Ridge. The downclimb from the notch is low 5th Class.
No special gear needed though the more timid might not like the Class-4 chimney. The chimney can possibly be avoided by diligent routefinding around it. A 30m rope would be sufficient if the chimney is not to your free-climbing liking.