Sorry, been a busy day for me.
Iron Lantern can't make Kryptonite, no Green Lantern can. But he could possibly create kryptonite radiation, achieving the same effect. Assuming his armor's energy construct abilities are like that of a GL ring, which they seemingly are.
Also Iron Lantern might give Brainy at least a decent amount of difficulty at Monopoly, since economics is arguably one of Earth-616s Anthony Stark's biggest skills in life, and while Stark Odinson hasn't had that much evidence he shares it, Harold on the other hand has a multi-billion dollar aviation company. Also every player is for themselves in Monopoly, so I expect Odinson to at least beat Kara at it, unless Brainy gets her first.