Gear list for boy scouts

Absolutely no levis IMO, iThey can get wet just from sweat they will be heavy, uncomfortable, and chafe them horribly.

Scouts usually travel to/from where they are going in Class A uniform. The official boy scout pants are nylon zip offs. Most troops allow them to wear any pants as long as some shade of green (because official is $50, but this is where they need the right ones.

Cotton underwear too, synthetic compression shorts at walmart are 8.99 dont need spare IMO.

Most boys do not change clothes or underwear on any camping trips, even "car camping".

need synthetic socks too, not cotton or they can get blisters badly. The official bsa socks that are part of the uniform are acrylic and will do.

I was part of a troop with a lot of low income scouts, So I have a few insights from that standpoint:
You should offer examples of what to buy, and where to buy them. Plus an estimated cost. Parent's can get especially worked up about having to spend to much money for kids to go camping.
Sierra trading post is also great, for socks. Especially if everyone in the troop, purchases them together with a coupon. You could get smart wools for $5 bucks or so.

For the shirt- (starter brand exercise shirt from walmart for around 8 bucks)
pants: should be nylon
socks: suggest wool hiking socks
first aid kit: make sure they have moleskin
you might recommend a fleece, depending on the season.

scouts should carry more than 2 liters of water, Its always a good idea to have more then that. Scouts aren't as good as experienced hikers at drinking water before they start hiking and loading up on it at water stops.