Got this request a lot to make a custom report back in my previous job. However epicor does offer the follow out of the box reports.
Slow Moving Stock: Material Management > Inventory Management > Reports > Slow Moving Stock
Obsolete Stock: Material Management > Inventory Mangment > Reports > Obsolete Stock
If you go about making your own, it would involved making a BAQ that looks at the last transaction for your specific part (Subquery). Whether you want that to be receiving into inventory (RcvDtl) or a specific transaction (PartTran). Depends on how you consider something to be slow/obsolete.