Yukizome-kun?! ...My, my, so you do have a sense of humor! I had thought that you were beyond that!

[ She sounds like she's chiding him a bit, but she's actually close to giggles. He may not want to call her Chisa, but, this was certainly a cute way of getting around it. ]

He clearly wants to play with you, though. But poor Cleffa is too small for him to really play with her...maybe Poliwhirl can play fetch with him a bit?