Pokemon 20th Anniversary
Where's Oddish? Bet you can't find Oddish.The Pokémon Company

Without strong character design, the Pokémon series wouldn't be anywhere near as successful. As phenomenal as the series' underpinning game design is, if audiences 20 years ago hadn't been presented with a colourful cast of characters that appealed, and which they wanted to collect, train and battle – none of it would have worked.

Ken Sugimori is the man responsible. One of the games industry's great unsung heroes, he designed all 151 original Pokémon himself and is still involved in the series, working as developer Game Freak's art director. He's overseen the designs of all 722 Pokémon (the latest of which was revealed earlier this month) but while the work has continued at a consistently high quality – there have been a couple of missteps.

Not every Pokémon can be a Pikachu or a Poliwhirl, a Mudkip or a Mewtwo, a Greninja or a Gengar. It's inevitable some will fall short of the high standards set by two decades of hits. So, here are some of the very worst designs from the series, ahead of its 20th anniversary on Saturday (27 February).

For balance, we've also selected our five favourite designs from each generation.

Dedenne

Pokemon Dedenne
Dedenne is an electric and fairy type, but mostly its a Pikachu wannabe.The Pokémon Company

There's no debating which Pokémon is the most recognisable, the most iconic, and so arguably the best designed – it's Pikachu. So really it's no surprise that Game Freak has tried to emulate that success. In Gen 2 we got Pichu, the Pokemon Pikachu evolved from, and Marill, a rotund water-type. Gen 3 had Azurill, who evolves into Marill. Gen 4 had Pachirisu, Gen 5 had Emolga, but Gen 6 had the most egregious knock-off of them all – Dedenne.

Klefki

Pokemon Klefki
Okay, so this Pokémon collects keys, but how do the keys get on the keyring?The Pokémon Company

A lot of Pokémon designs are similar because they're based on certain animals – mice, fish, lizards, bugs and dragons for example. Sometimes these can yield poor results (we'll get to that later) but there's another category that's almost universally bad – those based on inanimate objects.

Some Pokémon have verged on this territory before (Magnemite, Voltorb, Blastoise has cannons coming out of its shell) but never to such a barrel-scraping degree as Klefki, the living keyring. The keys aren't part of the animal itself, but how exactly do the keys get on there anyway? Does it self-mutilate? I don't like any of this.

Vanilluxe

Pokemon Vanilluxe
It might be the wafer straw that tips this over into awful, or how smug the right-hand face is.The Pokémon Company

Then there's this guy, the ice cream – the sentient, two-scoop ice cream. The reason we've plumped for Vanilluxe over its two previous incarnations (Vanillite and Vanillish) is that it also commits another design sin, one as old as the series itself.

When Ken Sugimori decided Diglett would evolve into Dugtrio and Doduo would become Dodrio back in the original games, he opened the door for evolutions that are essentially just the same again, but with more heads. It's fine in moderation, but can turn a lazy design into something worse still.

Garbodor

Pokemon Garbodor
Garbodor.The Pokémon Company

Literal garbage. I'm not entirely against the idea of a Pokémon looking like a pile of rubbish, but at least give it a better design than this. Muk and Grimer were just two piles of toxic sludge, but those worked. Garbodor is just a poorly designed mess of nothing in particular.

Druddigon

Pokemon Druddigon
Druddigon.The Pokémon Company

Earlier I mentioned dragon types, and how groups of Pokémon based on certain animals (mythical or otherwise) can also falter. Many are simply unimaginative, but Druddigon is just plain awful. It looks like a Pokémon design drawn by an eight-year-old in the back of a notebook. One that's little more than a T-Rex with wings made up mostly of jagged lines and coloured with the only two pens left in the pencil case. Cheap and bland.

Tangrowth

Pokemon Tangrowth
Tangrowth.The Pokémon Company

Another lazy design sin is concocting or expanding upon evolution trees for existing, popular Pokémon. In the case of the Eevees, it makes some logical sense to have type-specific evolutions beyond the initial water (Vapoereon), fire (Flareon) and electricity (Jolteon) types. It's produced some great results in the years since as well. There are exceptions however.

In Gen 2 we were told Pikachu actually evolved from Pichu, Clefairy evolved from Cleffa, Jigglypuff evolved from Igglybuff and that Slowbro evolves into Slowking – it's cheap and obvious. The worst instance of this however is the addition of Tangrowth in Gen 4's Diamond and Pearl – which evolves from the original line-up's Tangela. Its design also leaves a lot to be desired; it's just a larger Tangela with weird arms.

Jynx

Pokemon Jynx
Jynx.The Pokémon Company

Do we even need to explain this?

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