So there's quite a few missions i have had issues completing over the months from Mission 15 to 29, I've had a lot of difficulty finding guides for specific levels is there anyone than can give guidance. I remember at one point i was able to find help on the wiki with specific events and missions but it seems most of them there aren't any comments.
Starting at Mission 15-1 to 15-4, the plan is to get gems from all completing all of them.

-= 15-1 =-

Put the fastest squad in the top right camp, two squads in the top left camp, then the rest in the bottom camp. As long as the fast squad is strong enough to beat the two pest battles in its way (use the full light gauge the two light gems provided if needed) getting all three medals should be straightforward.

-= 15-2 =-

Put the slowest squad in the top right camp, put the fastest squad in the top left camp along with any squad that is below it in terms of 'rank' (i.e., if squad #3 is the fastest then pair them with either squad #4 or the helper squad), put the others in the middle camp. Any squad in the right camp has the shortest distance between them and the finish line so you want them to take as long as possible. Similarly, squads in the leftmost camp will have the longest path so you want at least one of them to be fast enough to reach the bottom right pest fight before any other squad reaches the finish line.

My #1 through #4 squads have 522, 586, 760 and 572 speed and after running this stage again my 522 squad was barely slow enough to not hit the finish line before my 760 squad could get to the last pest battle. So, use the Speed Up/Down ability on your Knights if needed.

-= 15-3 =-

Make sure there are two squads in the top left camp but past that where the squads are assigned isn't a big deal since all of the normal pest fights are crammed into the early sections of the mission. Attrition might be an issue since there are six pest nests none of your squads can clear out, but any squads in the center camp should be OK since chibi-pests will run into squads that started in the other two camps first.

-= 15-4 =-

Make sure there are at least two squads in the camp that has two light gems near the start. Ideally both squads have around the same amount of speed so that when the first squad unlocks a pest nest the second squad wipes it out before it can create chibi-pests.

Past that the main stumbling point will be the random tile before the rightmost pest battle. Four of my five squads went towards the pest nests instead of that battle when I went back through the stage, which would've been a two medal run for me if I hadn't gotten a full clear already.

-= 15-5 =-

Put the fastest squad by themselves in the lower left camp. Having only one squad in the lower left prevents the lock coming off of those bottom pest nests which limits chibi-pest generation to however long it takes the squads in the center camp to wipe out the active nests. Put as many squads in the top left camp as it takes to guarantee that those three pest battles get cleared out.

A random tile is again your primary obstacle to three medals, so the more squads that run into that tile on the center of the map the better your chances are of reaching that pest battle.

Damn your awesome! Okay i'm gonna complete these right now

Update: Stage 15 completed on first try! very helpful post

Anyone have a guide on 16-2,3,5?

Edit: Completed 16 by myself, moving forward i can probably figure out most of these myself, it looks like back when i was doing these missions my team was really weak and i was struggling a lot, now that i a strong team it's all pretty easy to complete

Does anyone have input on 19-3 i''ve failed it like 5 times with different configurations, I have an idea how to do it but the order might be off. Either 1 minion at the top ends up getting left or 1 minion at the bottom gets left.

For 19-3, try putting three squads in the bottom left camp and one squad in each of the other camps. That will give you two chances at each of the pest fights that are behind random movement tiles.

It's not required but putting the fastest squad in the center camp should keep them from reaching the finish line before the other squads clear out all of the pest fights on their paths.