FCC down trains use platform 2; Southern down trains use platform 2
(less often) or platform 3. I suspect FCC downs could be put into
platform 3 sometimes, but I've never seen it. However, even if a
platform change is required, there *aren't* any stairs at East Croydon
- both the street - platform level access, and the inter-platform
access, is by nice long ramps.

I guess it must depend on the time of day you pass through. Whenever I've
passed through in the morning peaks the FCC downs have all been using
platform 3, and during the day I've seen also seen many using platform 3.
During the evening peak you get the odd one routed onto the slow lines and
ending up in platform 5. Any Southern downs coming in on the slow lines
also tend to end up on platform 5.

However as you say the real issue for the OP is that there aren't any stairs
to worry about, you just get the occasional frantic dash down and up the
ramps if the platform is changed at the last moment.

G.