I have big issues with most of the new evos introduced in Gen IV.
Magmortar, Rhyperior, Tangrowth, Lickilicky, Magnezone, Togekiss, Electivire....they're all just fat versions of the previous Pokémon. Mamoswine was the only good one of the new evos. (weavile is debatable, but just adding new spikes on his head is hardly a creative idea). I'd agree Rhyperior is the worst of the new ones.
Double cones are definitely a thing.
Whimsicott is one of my favorite Pokémon of all time, and the surprise of the green thing on its back was an added bonus
I can forgive the ass-for-a-mouth Pokémon, because it reminds me of this scene from a chinese cartoon. Also, pyukumyuku is a cool name.
As far as starters go, I've always had beef with Feraligatr. Such a boring final stage.
All of the Gen II starters have super boring middle and final stages, but feraligatr takes the cake for least creativity.
I have a much shortened list:
GEN I
PinsirThat stupid mouth
and the pointless spikes on his horns/pincers
and that terrible color scheme (which is somehow made WORSE with his mega)
I'm so happy for Vikavolt to save the stag beetle image from this atrocity
Dugtrio (in X/Y)
Dugtrio on it's own is cool
Dugtrio MOVING, all 3 at varying directions and speeds, is disturbing
GEN II
See above
GEN III
Huntail / GorebyssThey look like stock enemies from a water level in any bad RPG. They're such filler Pokémon it hurts
not to mention, functionally, they're trade evolution and look nothing like Clamperl.
GEN IV
See above
GEN V
There were a lot of Pokémon that were just there, but none that stood out to me as being truly awful.
GEN VI
Slurpuffjust a gross Pokémon to look at
I don't know why anyone thought it was a good idea
and a bad example for the exploration of the new fairy type
GEN VII
There are some really bad ones, but I don't know the names. Let me go by descriptions
Lip Fish
The Stupid Old Dragon
Trump Weasel
Red Panda + Red Panda's dad
Sandhouse + SandcastleIt's funny because half of Gen VII is GREAT while the rest are just there (at best).