An interesting one with lots of ambiguity this week.
I'm going to start by assuming that a standard Neopet species means all Neopet species, but in one of the basic colors. If you want to exclude limited edition and restricted creation Neopets, then you'll take out:
Chomby - limited edition
Cybunny - limited edition
Draik - need a Draik egg
Grundo - Space Adoption Agency
Hissi - limited edition
Jetsam - limited edition
Kiko - limited edition
Koi - limited edition
Krawk - from Krawk petpet
Lutari - very limited edition
Poogle - limited edition
Tonu - limited edition
Then there is the matter of what is a toe. Since the Ixi is specified as having no toes, I assumed the Kau and the Moehog also had no toes, even though their hooves appear split as well.
I generally considered species to be either 0, 2 or 4-footed, depending on what position they were shown in at the Rainbow Pool in the basic colors. (I used red.) I assumed that species shown as standing on 3 feet should have all 4 feet counted. I also assumed the Buzz would stand on 2 feet when it landed.
There are certain discrepancies with the older artwork shown on the all Neopets page
http://www.neopets.com/allpets.phtml. In particular:
Blumaroo is on tail instead of feet
Draik is on tail instead of feet
Lutari appears quadripedal instead of bipedal
Meerca is on tail instead of feet
Skeith is on four paws instead of two
Tuskaninny has two paws on the ground instead of standing on the tail
Finally, one of the most interesting questions is whether a Lenny has 4 toes or 6. Do we count the two back-pointing portions of the feet as toes, as we normally would with a bird? Although bird-like as well, the Pteri doesn't seem to have this issue.
One additional issue is that the raised forefoot of the Cybunny appears to have 4 toes, although the rest of the feet have 3. I assumed that this was a minor error in the drawing and left the Cybunny with a total of 12 toes.