There are specific commodities that are challenging in many ways.
There are some, such as hazmat that go without saying, due to exposure to employees.
There are some that are challenging due to potential damage from additional handling, such as wallboard which is easily damaged by hitting corners or simply from the weather. When it is dry the wallboard is brittle, and when it is humid the wallboard is soft.
Slip sheet product can be challenging especially if the slip sheets are cardboard that easily tear.
Liquid propane can be difficult in hot climates since a portion of the car can turn to gas making transload difficult or impossible.
Rolled paper stock can be challenging because a simple dent can damage many feet of paper.
Bulk commodities that require heavy PPE in hot climates can be challenging. Safety requirements such as PPE, fall restraint, and specific protocol can make certain commodities challenging.
Handling equipment can be challenging in terms of cost: paper roll clamps, box clamps, slip sheet clamps, lumber forks, coil rods, etc.
Even weather can impact handling. In the northern transloads, I switched from forklifts to articulated loader because I could drop the forks and put on blades and buckets to move snow.
All in all, all commodities have challenges that transloaders need to be aware of to be successful.