Ekans
From above, if it tucks its tale in.
(source: bulbagarden.net)
Parasect
Again, if it tucks in.
Ludicolo
From above.
Seedot
From above.
Castform (Normal form)
From above.
Shuppet
I think the skirt can be tucked in so it looks circular from above.
(source: bulbagarden.net)
Snorunt
Again, I think the hands can be tucked in and it will be circular from above.
(source: bulbagarden.net)
Drifblim
From above. It's the evolved form of Drifloon which was mentioned in another answer, but, well, they are different Pokémon and Drifblim wasn't explicitly mentioned yet, so...
Happiny
From above, of course.
(source: bulbagarden.net)
Solosis
It's... literally a sphere...
Vanillite
The clouds in the picture are NOT a part of the Pokémon, so - from above.
(source: bulbagarden.net)
Amoonguss
Another evolved form that wasn't mentioned before. Just needs to tuck its hands in before viewing from above.
(source: bulbagarden.net)
Beheeyem
While I'm not quite certain about it's previous evolution (Elgyem), Beehyem can DEFINITELY look round when viewed from above.
(source: bulbagarden.net)
Litwick
Is a silhouette a shadow and does a flame affect it then? I think not, so - round from above!
(source: bulbagarden.net)
And there were a bunch of others that I wasn't really sure about. To be honest, I wouldn't have included Jigglypuff myself because I think its hands or ears would distort the circle from any angle. It was for this exact reason I omitted a whole bunch of others like Igglybuff, Kabuto, Togepi, Sunkern, Swinub and others.
