Since we have included a backpack approach for these summits. the "route" begins from where the West Maroon Trail makes the first crossing from the west to the east side of the creek. When we climbed these summits in 1993, the winter of that year was a high snow year in the Colorado mountains. Those heavy snows persisted well into the summer, so our route decisions were influenced by those conditions. The three summits south of Pyramid were all climbed on the same day which was July 23, 1993. Most rate this a Class 3 climb on the assumption you stay mostly in the couloir. The difficulties we encountered staying out on the rock rib are what cause us to give this a Class 4 rating.
From the vicinity of the suggested campsite, locate where the trail crosses to the east side of the creek and make the crossing however you can. There was no log bridge of any kind at the time we did this. On this occasion, there was a snow-bridge that made crossing easy. Once across, head east up through trees, working your way along by finding whatever trails you can - some game, some man-established. There are an alternating series of cliffs and benches with areas of trees. In 1993, we found a fairly direct, cairned trail that led us through a boulder field, then alongside a steep, snow-filled gully to another bench area. From there, the route into the upper basin at about 11,800 feet opens up rather naturally. By the time of this writing, we would expect there to be a well-used/marked trail.
Once into this upper basin, take some time to oreint yourself and carefully identify each of the three summits - Thunder Pyramid, Lightning Pyramid and UN13,631B. You want to identify the correct couloir that ends up at a saddle between Thunder and Lightning Pyramid. Look for something you would not relish going up and that will likely be it. You should be almost directly west of the proper couloir. It empties onto a large talus field which rises about 400 feet in elevation to a cone that spreads out from the base of the couloir. The talus will then narrow into the couloir itself. In 1993, this couloir was filled with snow as far up as we could see. It was steep enough to leave us desiring crampons, which we did not have, but we did have ice axes. Several hundred feet up, the couloir passes through a particularly narrow section and appeared to even pass over some angled cliffs. G&M recommended avoiding the couloir in that section by following alongside on the exposed rock for a ways before re-entering. Because of the snow conditions, what we decided to do was to stay on the right-hand side of the couloir from the outset. We intended to remain on the rock rib until past the narrow section of couloir, then drop in at the first available spot. That never happened. If you find snow here, and it's early morning, it should be fairly firm for several hours before sun gets on it. We found the snow in the couloir to be hard and icy, which became yet another reason for staying out of it.
Climbing on the rock rib on the right side of the couloir was somewhat exposed for much of the way. It consisted mostly of 3rd class scrambling on relatively stable rock with at least one point that required a minimum 4th class maneuver to get up across a rock band. Caution had to be maintained at all times. This was fairly continuous scrambling for nearly 1,200 vertical feet. It's easy to cut rocks loose and they will hurtle down with amazing speed. Helmets are highly advised. As you approach the summit ridge, the angle of ascent will moderate. By remaining on the rock rib and never entering the couloir, we came out just north of the summit by about 200 feet. The final scramble will be the easiest thing you've done for the last hour.
From this summit, peruse the ridge in both directions, but mostly concentrate on reaching Thunder Pyramid to the north. If you were hoping for something easier than what you just did, you will be disappointed. Catch your breath and prepare to meet Thunder Pyramid. Our climbing partner for this day suggested that successfully navigating terrain like this may be more a matter of "dumb luck" than any actual skill we possess.
Links to other information, routes & trip reports for this peak that may be helpful.