It's A Trap!

No, not that kind of trap! This one's a girl:
Pokemon: Trapinch
Ability: Velvet Underground
Velvet Underground is an ability that allows the user to generate an inescapable and indestructible cage around an area. The cage is formed by having the two halves come out from either side of the area to be enclosed and then coming together perfectly at the apex. The entire cage is only a semicircle and can be summoned from any sufficiently large surface (Even vertical walls). If the cage has to go through something to close up, it will phase through it harmlessly. Anything within the cage cannot be harmed by anything from outside, and the same holds true vice-versa. The gaps in the cage serve only as a window and lets only light, sound, and air pass through. Anything else will just bump into the gaps as though there is a sheet of glass there. The inside of the cage is lined with spikes to prevent people from attempting to escape. Trapinch seems innocent enough, but she has some really crazy ideas for games. And nobody can escape her...