This is the easy route to the top. There is very little routefinding but there are two ways to climb the South Face which start at different points. Most of this route is similiar to the South Gully route of Spider Mountain. The gear needed for both is the same, though some weaker parties may wish to have a 30m scramble rope here.
Formidable can be climbed from a Ptarmigan Traverse camp near Pt. 7285 south of the summit in as little as 3 hours round trip. In this regard, many PTravelers give it a go. The views from the summit are outstanding.
Approaching the Face
From Spider-Formidable Col, descend from the narrow eastern notch down steep snow or in the moat beside the snow for about 150 vertical feet until it is feasible to begin contouring right (west). Continue westward over mostly slabs and snow (crampons?) then heather and minor rock outcrops. You will be aiming for the obvious saddle north of Pt. 7285. There is a couple hundred feet of re-ascending to make this saddle from the Ptarmigan Traverse path.
From the saddle look across toward Formidable's South Face. There are two basins split by a cleaver. The farther (westernmost) basin is where you will be going. The idea is to mount the cleaver as high as possible before it rises up to form a buttress. But first you have to get into the nearer basin. There is a loose, nefarious gully on the right. It looks like the only way but DON'T GO THAT WAY. Instead, descend to its left on a steep heather rib. The heather transitions to sandy benches then blocks and scrambling (Class 3 max). The rib's base is left of the gully and so at some point you will have to sketch across the gully on hard dirt.
Get away from the gully and angle up and right roughly northwestward. Gain the cleaver at around 7,400 ft. Class 3 to get onto the cleaver. Look for a cairn.
Ascend the cleaver to its apex then bear left across the base of a permanent snowslope to just about where the upper basin below the South Face opens up.
South Face, Gully Option
Climb up and left to a hidden gully (c. 7,800 ft). Climb up the gully for about 100 feet then either cut right to a smaller gully or continue up the main gully. The smaller gully quickly turns into an alcove requiring some Class 4/5 for a few feet to get to its top. The main gully contains some Class 4 steps much like Spider Mountain's gully. Eventually, move out of the main gully to reach the same point as the top of the alcove, which is the base of a rib. There is a cairn here.
From the top of the alcove look left (east) along a ledge that leads all the way across the face to the far buttress. If you look close you will see a cairn off in the distance. This is where the other option detailed below comes up.
Now simply continue up the rib. It bears directly to the summit. Stay as close to it as possible, moving left or right as necessary to make for easier scrambling. Class 3.
South Face, Ledge Option
From the permanent snowfield where the cleaver ends arc up and then right to the backside (west side) of a wall looming over the snow. Exit the snow and onto Class 3 rock. Climb up and then left to a handy ledge. This ledge curves all the way around the face at about 8,000 ft to reach the top of the alcove mentioned in the previous section. Note that the alcove cannot be seen from its top (that is, you are already above it at this point).
There is one deep chasm to cross on the ledge. A scramble rope may be handy here. Both sides have some exposure difficulties. Care must be taken.
All in all this option is easier then the gully option but the deep chasm almost negates this. I guess I recommend this option but it is not at all obvious from below (i.e., from below the face).
Time = 3 hours from Spider-Formidable Col; 5 hours round-trip
Gain = ~1,700 ft; 2,000 ft round-trip
Distance = 1.5 miles from Spider-Formidable Col
Descend the way you came up, taking either of the two options above. I recommend the ledge option.
Ice axe (early season only)
Lightweight crampons (especially to descend the snowfinger on south side of Spider-Formidable Col if no moat is available)
Trekking poles (will probably be handy for the tedious traverse across the south slopes)
Scramble rope (with protection and harness as necessary)