Items such as Terrain Extender and the Rocks are notable in that without telling the opponent that they're being held, they are revealed when the weather or terrain lasts all 8 turns. It's also easy to track which Pokemon caused the weather/terrain and determine which Pokemon to be holding the item. However, Showdown doesn't display these items as being held.
Currently the only Items I can think of this applying to are Heat / Icy / Damp / Smooth Rock, Terrain Extender, Grip Claw and Light Clay, but there may be more I'm missing.
Currently the only Items I can think of this applying to are Heat / Icy / Damp / Smooth Rock, Terrain Extender, Grip Claw and Light Clay, but there may be more I'm missing.