Well, now that's the cutest portable charger she's ever seen.

Of course Madoka knows it's a Pokemon. She doesn't even have to know, she can just tell from looking at it - especially since Madoka both knows that Katsuya has been handing them out, and that it was his cute pony in the first place that had been cleansing Mami's gem. So there probably were more out there that could do that, right?

"Oh, she's so cute..!" Okay, it's more important that it's keeping Mami safe, but clearly we can't ignore that aspect of it. "I'm glad you have her with you, Mami-san. I imagine Katsuya-san can't always be around, after all.."