Why does everyone hate Feebas and Shuckle? They need more love, people! ;_; *Huggles them.*
Anyway, the top three ugliest Pokémon in my opinion are:
Giradina because I simply fail to see the coolness in a mutated maggot with freaky wings and legs.
Nuzleaf. Shiftry is cool, but Nuzleaf is just meh... =\
Pinpuku. A pink ball with ugly pants. Yay. ._.
oh yeah... miltank... its ugly and weak....
Miltank, weak? L-M-A-O! Miltank has awesome HP, Defense and Speed and decent Attack and Sp.Def, making its only low stat Sp.Atk, which it wouldn't have any use of anyway. Combined with a large movepool, only one weakness and a resistance to Fire and Ice thanks to Thick Fat, it makes Miltank a very deadly Pokémon in the right hands.
Due to its good stats, Miltank can play a wide variety of roles in battle, such as cleric, sponge, staller, (even though they are lol) tank, a Curser, a Subpuncher and even a CBer even though Miltank is most useful as a cleric. Plus, Miltank looks cool. >O
Of course I can't change your opinion about its appearance, but Miltank is everything but weak, and if you have failed to realize that, you have probably tried making Miltank a sucky special sweeper, which is the most stupid thing you can do to poor, little Miltank. ._.