Underground Digging

Well frankly as far as I'm concerned there is no point to them, unless you enjoy galivanting around the underground with your friends setting traps and building secret bases and the like. I was never such a fan of that myself
Anyway you can trade the spheres to hikers underground for stuff which is, like I said for putting in your secret base or playing with you friends. Stuff like jump mat left, or digger drill, or flower trap... That kinda stuff. If you are interested in that you may notice the hikers sometime want like blue size 40, but you can't find more then ~20 by digging. You can add the spheres together by burying them in the ground in the same place, but the addition is a little wonky. Bury a 20 sphere first, then a 16 sphere and you magically get like a 23 or 24 sphere. Yay!!

Okay, no one called you a noob except yourself. No one will call you a noob, and if they do, their the noob. Actually, there is a point to the brightly colored spheres that you can find, and dig up everywhere. I know, imagine my surprise when I found that out. You can use the spheres to buy items, and traps from the hikers that randomly pop up all over the place. Apart from buying stuff with the spheres, you can bury them for other people to dig up. That's it.

The multicolored shards are used for getting free TMs from a lady that livers near the swamp. The lady is left of the Route before Pastoria City. She will give you Sunny Day, Rain Dance, Sand Storm and another one that I can't really remember. You have to give her 10 of a certain color of shard.

Acgmindmaster12

The colored shards are used to get stones to heklp evole Pokemon go to a house to give the shards to the lady and their you go

All that you get for tan of the same colour shard, are field TM's eg. Rain Dance. You trade them t a person west of Pastoria.

P.S. Could someone please rate my team "tricky14! 1st"
Hope this helps =)