-cup - depends on the pitching
-Shin guards - 1 year
-Helmet - 1 -2 years if treated well. The usual issue with the helmet is missing parts due to the user's inability to locate and use the correct screwdriver to keep stuff properly attached/tightened.
-Chest protector - good as long as it still matches the helmet and shin guards
-Gloves - 2 - 4 years if treated well. A catchers glove that "looks good" maybe past its useful life if it is loose and/or floppy /streched out etc...