Well she wants to be a pokemon more than anything right? I would tell her that I understand how she feels, I won't judge her for it, and that it's okay for her to express herself around me. We would spend a while talking about her feelings of being a pokemon while drinking tea or having light snacks, and eventually she would open up to me a bit more.
"Anon, it's so nice to finally meet someone who understands how I feel..." She would say.
I would reassure her that I completely support her and want her to be comfortable with herself. She would blush slightly, take another sip of her tea with a trembling hand, and shakily ask me-
"W-would it be okay if...just for tonight...I could pretend to be your pokemon?"
A little taken aback, I would be a bit nervous about the situation. Roleplaying pokemon? With an adult woman? I would take a hasty sip of my tea, avoiding eye contact with her out of embarrassment. She would immediately pick up on the feeling, blushing intensely and burying her face in her decorated sleeves.
"I'm sorry anon" she would say, blinking back tears "It's just something stupid I've always wanted to try, I thought maybe you would be comfortable enough to help me with it..."
I would apologize and tell her that she has nothing to be embarrassed about, that I was just a little shocked when she asked me. A bit reluctantly, but still wanting to make her happy, I would say that yes, just for tonight, she could be my pokemon. She would lift her head from her exaggerated fairy outfit, wipe the tears away delicately with her sleeve, and say-
"Y-you mean it anon? You'll do this for me?"
Of course, I'd tell her. If it means this much to her, I would love to help her.
"Valerie!" She would exclaim, throwing her arms around me.