Each generation had Pokémon that could be considered as bad or uncreative or just plain embarrassing:
Gen 5 - Ice cream cones, gears and trash bags (although, if you didn't realize, there's a theme for Koffing, Grimer and Trubbish: the pollution of, respectively, air, water and land) .
Gen 4 - A skunk with a butt for a face, a rabbit with extremely feminine shapes, a mirror with eyes that evolved into a bell, the infamous Bidoof.
Gen 3 - A heart-shaped fish barely able to do anything, two very obvious Pichu clones, a stomach with a face, a spinning top, a bell, a Moon and a Sun.
Gen 2 - The alphabet, a pinecone, whatever Dunsparce and Shuckle are, and the ultimate non-sequitur: a fish evolving into an octopus.
Gen 1 - Magnets, Poké balls, eggs, noodles (or whatever Tangela is) , Pokémon that were actually called with regular words: Golem, Abra, Kadabra, Alakazam, Electrode and Kabuto (a kabuto is an ancient Japanese helmet) ; tadpoles with visible innards, moles straight out of a "whac-a-mole" game, two evolutions actually being groups of three first stage Pokémon, and (talk about running out of ideas) a three-stage evolutionary line that was put in the game twice in a row, and the second line only had minor alterations (same basic species, one evolutionary line being all females, the other being all males, you know what I'm talking about) .
To me, the quality of the designs remains consistent. Each generation has critters that are cute or menacing or derpy or awesome... there are all kinds of Pokémon, and that's a big part of what I like about this series.