(digs through browser)
adlib - [ no need in most cases ]
ahx - [ no need ]
allgear - Project file from DAW used (may not work most of the time since some DAWs/plugins aren't free, but if you wanna throw in your FL Studio, Reason, Cubase, Logic Pro, etc. projects, by all means)
amigamod - [ no need ]
ansi - [ no need ]
ascii - [ no need ]
aym - see ahx
bytebeat - [ no need ]
bytebeat1k - [ no need ]
channelf - see ahx
chipbattle_art - Project file if necessary (no need if you use something like MS Paint or something with no layers)(also may not work sometimes since some image editors aren't free; sorry Photoshop)
deflemask - [ no need ]
doom - [ no need? ]
famitracker - [ no need ]
fsound - [ no need ]
gameboy - Project files from the source tracker if applicable
hes - see ahx
html - [ no need ]
html5 - [ no need ]
mariopaint - [ no need ]
mariopantse - [ no need ]
midi - Project files from DAW used (see allgear for reasons why it may not work)
mixbattle_art - Project files from image editor used (see chipbattle_art for reasons why it may not work)
mod8kto64k - [ no need ]
mptm - [ no need ]
nsf* - Project files from FamiTracker or MML source
ntrq - [ no need ]
panda - Project files from tracker if done externally; otherwise, no need
pixel - see chipbattle_art
pxtone - [ no need ]
remix - see allgear
renoise - [ no need ]
s3xmodit - [ no need ]
sample - [ no need ]
sap* - see ahx
sgen - Project files from VGM Music Maker or other sources
sid - see ahx
sms - see ahx
spc - Project files from the tools used to make it (or a s3xmodit file because we all know most spc makers just use a converter lol)
sunvox - [ no need ]
svg - [ no need ]
tia - see ahx
vic20 - see ahx
wildchip - see ahx or allgear
zxbeep - see ahx
I may be wrong on some of these :o
So, in summary (and taking b00daw's corrections into consideration):
Certainly (source can be provided and anyone can access it)
aym channelf gameboy hes nsf nsfplus nsf_classic sap sapx2 sgen sid sms spc tia vic20 zxbeep
Maybe (source can be provided, but accessibility may be limited)
allgear chipbattle_art doom midi mixbattle_art panda pixel remix wildchip
No Need (format is synonymous with source)
adlib ahx amigamod ansi ascii bytebeat bytebeat1k deflemask famitracker fsound html html5 mariopaint mariopantse mod8k mod12k mod16k mod24k mod32k mod48k mod64k mptm ntrq pxtone renoise s3xmodit sample sunvox svg