Yes, but rare.
All stones must be obtained by trading shards to the hunter west of mossdeep city shards can be found underwater near the hunter's house.
Red shards can be found all over underwater areas
Don't you mean leaf shards? There all found underwater near the hunters house.
Clamperls are found when you use Dive, and roam in the grassy-areas. ^_^
Green shards are found underneath the water (or in the sand on islands) while diving.
You can find them underwater and if you catch a luvdisc they may be holding a heart scale.
Blue shards are found underneath the water while diving.
Dive underwater and search for blue shards. Then, once you've found one, go to Hunter's House (to the left of Mossdeep city, on route 124), and he'll trade you a water stone for it.
There is a 5% chance that a wild Pikachu is holding a light ball. Pikachu can be found in the safari zone, but it is rare.
There are four shards in Pokemon Platinum- red, blue, green and yellow. They can all be found in the Underground.
A wild Pikachu found in the Safari Zone may be holding one, around a 5% chance.
I have found shards while rock smashing ,smash able rocks. I do not know of other ways to get hem,