dat00.s - some graphics stuff, pt_801EF84 is related to battle phrases that appear in the center of the screen (e.g. "ENEMY DELETED")
dat01.s - some of it is battle stuff, some of it is unknown
dat03.s - map script/map related stuff (end of asm03_2.s)
dat04.s - map script/map related stuff (asm04.s)
dat05.s - map script/map related stuff (asm05.s)
dat06.s - map script/map related stuff (asm06.s)
dat07.s - map script/map related stuff (asm07.s)
dat08.s - map script/map related stuff (asm08.s)
dat09.s - map script/map related stuff (asm09.s)
asm10.s - map script/map related stuff (contains two maps and includes data for first map in file)
dat10.s - map script/map related stuff (map data for 2nd map in asm10.s)
asm11.s - map script/map related stuff (contains four maps, includes data for first three maps in file)
dat11.s - map script/map related stuff (map data for 4th map in asm11.s)
dat12.s - map script/map related stuff (asm12.s)
dat13.s - map script/map related stuff (asm13.s)
asm14.s - map script/map related stuff (contains one map, but partially includes data because IDA detected an inline asm function in map script)
dat14.s - map script/map related stuff (rest of data for asm14.s)
dat15.s - map script/map related stuff (asm15.s)
dat16.s - map script/map related stuff (asm16.s)
dat17.s - map script/map related stuff (asm17.s)
dat18.s - map script/map related stuff (asm18.s)
dat19.s - map script/map related stuff (asm19.s)
dat20.s - map script/map related stuff (asm20.s)
dat21.s - unsure. this looks like a map script (data looks very uneven), but I can't find a reference to it. perhaps it was removed data? also, there are a few inline functions in it as well
dat22.s - more unknown bytecode? again, doesn't seem to be referenced.
asm23.s - even more unknown bytecode! first third of the file is mostly data, rest of file are functions that are only referenced inside the file?
dat23.s - more unknown bytecode
asm24.s - more unknown bytecode, mixed with code
dat24.s - more unknown bytecode
dat25.s - more unknown bytecode. also, asm25.s only has three nonlocal functions
dat26.s - more unknown bytecode, mixed in with asm
dat27.s - more unknown bytecode
dat28.s - mystery data is defined here, maybe some other unknown structs
dat29.s - unknown single struct? not sure how it's accessed, but IDA thinks it's a byte array
dat30.s - random encounter data
dat31.s - (fake data)
dat32.s - some structs. pointed to by the table at pt_8121200, indexed by getPETNaviSelect. format of pt_8121200 is table of pointers, with these pointers pointing to a single pointer, with that pointer pointing to a table of pointers, with these pointers pointing to an unknown struct terminated by -1. also, some fake data (asm) here.
dat33.s - (fake data)
dat34.s - (fake data)
dat35.s - (fake data)
dat36.s - unknown, first half sort of looks like bytecode but it probably isn't, second half looks like a consistent struct
dat37.s - rodata for libraries
dat38_0.s - fake pointer, FIXME
dat38_5.s - not included in the build (oops)
dat38_30.s - sprites
dat38_31.s - sprites, fakepointers: byte_8340031, byte_8340901
dat38_32.s - sprites, fakepointers: byte_835083F, byte_8370817
dat38_33.s - sprites, unmarked sprite pointers: byte_83971C0, byte_8398048, fakepointers: byte_83C0710, byte_83C0716, (more but will find them later)
from here on, not checking for fakepointers
dat38_34.s - sprites
(stopped for now, most of this is probably sprites, chatbox scripts, gfx, or some other bulk data)