I've looked in all the Tanoby Chambers and found every type of Unown except E, O, ?, and !. What are the odds of finding them in the relevant chambers? They don't seem to be even odds... I've walked enough steps in the Monean Chamber to hatch a Bulbasaur egg, and still can't find a ? Unown.

If there is data available on the proportions of Unown found in the chambers, it might be a good idea to include it in the Sevii Guide, by listing the types of Unown in each chamber in the same manner as the other wild Pokemon lists.

The game differentiates Unown through DVs I think, so it's completely random as to which Unown appear. I don't know the exact calculation, so I can't even give you an approximate probability.

Ah... so I just keep looking, I guess? I hope the ? and ! Unown aren't THAT rare... but, since I've found 24 out of 28 Unown so far, I can't be doing too badly. Thanks anyway.

EDIT: ... I looked and looked and looked, and finally managed to capture every single type of Unown. My collection is complete! Woohoo!!!