21: Close to intended. Only the way you stopped the Fencer and the lemming coming from above at the end was a little different, I used a Bomber there.
22: Close to intended. You just cancelled the Miner a little earlier so that he didn't have to jump over to where the crowd was being contained. Usually, that Basher at the end re-frees the pioneer along with the crowd, because he gets trapped inside the anchor as well.
23: This is a fine alternative solution. Especially the end part is still as intended. After all the backroutes this level has been plagued by during testing, this is much more than I was daring to hope for!
24: This is very similar to the alternative solution kaywhyn found. If you didn't find it that hard, good on you!
It seems like he struggled with this quite a bit, and he is one of our most adept solvers. Though that may have been the mental-state effect at work in his case, since he was one of my testers, and thus has played several previous iterations of this level, finding solutions (=backroutes) in the process that no longer work now. That may have made it harder for him to find the intended or his alternative solution than for somebody who approaches this level for the first time.
25: Very close to intended. You lost quite a few lemmings at the end who splatted just in front of the updraft. But that's one of the reasons why the save requirement is comparatively lenient. I used a couple of Jumpers to get the pioneer further ahead when platforming over the updraft. You also saved one Basher, which you could have used to bash through the pillar to get the pioneer back to bash through the one-way arrows. Somehow though, nobody has felt the need to do this yet.
26: That was an interesting choice to create a Digger shaft to allow the other Climbers to access the relevant section of the level more quickly. You're also only the second person to use a second Miner tunnel to get the lemmings over the first one, instead of a Basher tunnel.
27: Very close to intended, just the way you contained the crowd was a little different.
28: Very close to intended, I just didn't know it was possible to do the Miner work on the left side with a Climber without having him splat at some point. But you took care of that problem by digging and cancelling the Digger, thus making the wall no longer climbable. You used all the skills in the process, so this is a perfectly fine solution!
29: Very close to intended; I stoned the Climber at the end instead of a lemming from the crowd, because in my solution, the Climber would die otherwise anyway (since not enough Jumpers remain). You did things slightly differently, so you had precisely those two Jumpers to get the Climber off the walls that would have lead him to his death. You still used all the skills in the end nontheless. The great thing about your solution though is that it demonstrates the relative timing between the two worker lemmings isn't actually as crucial as it was in my intended solution. (Because in the intended one, you need to get the Climber to turn around before the lemming on the left goes through the one-way wall, lest the Climber would go through the tunnel, too, climb up, and die from the spike trap.)
30: This one is open-ended. Glad to see you had to use all the Builders, Jumpers, Shimmiers, as well as all of the destructive skills (except for the Bombers, of course, which you can't use anyway due to the save requirement).