You, a trainer, was just practicing how you battle all alone with your pokemon, a Greninja. Your male pokemon practicing his moves on a tree, aiming to get stronger with you. There were slight unusual things happening between you and your pokemon whenever you battled. Your Greninja would suddenly get surrounded by gushing water, having some unusual markings on him as well mid battle. You could see what's happening around him, as if you were in his point of view, or even became one with him. After battling however, you would suddenly feel tired, while Greninja would go back to his original form, without the markings and water surrounding him. This time, while training, you and your pokemon became one again, but mid-training, you suddenly feel paralyzed. You can't move, no matter what you do. Then, you fall to your knees. Your Greninja goes back to its original form as well, and falls to it's knees because of the synchronization. He, however, quickly stands up and approaches you, kneeling down to take a closer look. He's definitely concerned, speaking up, saying:

"Gre...! Greninja!"

Since all a pokemon can say is their own name.