"Aah, an excellent question!" The Professor responded, preparing to answer the question. "Shadow Pokémon are quite mysterious, as they usually appear as normal Pokémon. It can actually be quite difficult to tell if a Pokémon is a Shadow Pokémon. But thankfully back when I hunted for them, we had a piece of technology known as an Aura Reader. Like the Purification Chamber, it was made by my father, and Professor Krane. It turned out that Shadow Pokémon emitted an odd aura that was invisible to the human eye, purple in color. Though we couldn't produce this technology many times over in case the Aura Reader stopped working, so we had to find other methods of identifying a Shadow Pokémon. Studies have shown that Shadow Pokémon are incredibly full of power, fueled by their anger and hatred. One way to spot a Shadow Pokémon is by simply seeing how it reacts to situations given to it. The offer to battle, for example. Most Pokémon would be willing, yes. But a Shadow would viciously step forward and insist on it happening. They also have incredible battling ability, showing great strength of both mind and body, one more than the other, depending on the Pokémon. They show no mercy in battle, willing to drain the opponent's strength to the bare minimum needed for survival. Some attacks in the past have left both Pokémon and Trainers fainted, people passing by happening to recover anybody to meet such a fate and thankfully getting them proper care. It can take days, even weeks, for somebody to wake up after an assault from a Shadow Pokémon. Cipher liked to make Shadow Pokémon out of species' that would appear weak to others, throwing them off guard if they were searching specifically for one. I..."

He paused for a moment, before continuing. "... Doubt that you will see an actual Shadow Pokémon anytime soon, but it never hurts to be wary of certain species' that seem to be preforming too well for their skill level, especially against highly trained Pokémon." Finishing his explanation, he stared at the hallway ahead, a neutral expression on his face. "Forgive me if that wasn't the most informative explanation, it's all we really know about identifying them without an Aura Reader. Hopefully it was enough to answer your question."