Following Platinum is cool, but simple. Just adds following Pokemon like in HGSS. There's also Renegade Platinum by Dray, which is a diffculty and completion hack, and a combo of both the above hacks. Otherwise, DS Pokemon hacks are kinda sparse.

You might just wanna inject some older gen hacks. Try Dark Violet, a reimagining of gen 1, or Dreams, a completely original hack with Fakemon and a region based on Florida. Both are fun.