The titles says it all....If it doesn't, well sorry >>
What do you think is the worst Pokemon DESIGNS? Not the worst overall, just the worst design. (Although the two are highly related often, look at Luvdisc

)
In my opinion, the Pokemon with the worst design is Infernape. it's name is even unoriginal.
What kind of person would chose to create a creature like this?

It's obvious that they just slapped together this creature at the last minute to coincide with it's previous forms. Sorry to Infernape lovers (it's actually a good Pokemon in battle) but I cannot stand it's design.