Just saw this on Discord a few minutes ago, and while it's a bit of a stretch, it's interesting none the less:
Basically, Wario's house in Gold has a nest with eggs on it, and said eggs look quite a bit like those laid by hen in Wario Land 2. Hence the theory is, Wario kept the hen when he moved from the castle on Kitchen Island to Diamond City, and the nest on the roof is its nest in said location.
But yeah, what do you think? Is this a plausible theory or not?
Basically, Wario's house in Gold has a nest with eggs on it, and said eggs look quite a bit like those laid by hen in Wario Land 2. Hence the theory is, Wario kept the hen when he moved from the castle on Kitchen Island to Diamond City, and the nest on the roof is its nest in said location.
But yeah, what do you think? Is this a plausible theory or not?