>>30853143I'm not entirely sure, but I think I just had to keep 1 slot in my party and the machine would quickly place Mew there without trading for it. The typical trade animation would show on the TV and it was done pretty quickly. I also got a sticker to put on the back of the cart which by now has faded almost entirely.
Apparently they also used this thing as well, which is probably what you're thinking of.
