Breakfast only, however if you book an ADR between 1:00-1:40PM for lunch you get reserved seating for Nemo, which was great, we were right up front. We thought our lunch at Tusker House was one of the highlights of our trip in January.
We did a 10:30 breakfast so that we got the characters. The food is quite varied and easily worked as an early lunch as there were many items that were not typical breakfast items.