The Tokyopop translation of the manga, which gave characters terrible catchphrases that clashed with their personalities (such as Ojou Minto's "Bust a move, girl") or just sounded awful (Ichigo's "Shocker!").
And then there was the 4KidsMew Mew Power translation of the anime, which gave Ichigo such embarrassing lines as "Mew Mew Style/Mew Mew Grace/Mew Mew Power/In Your Face!"
Likewise, to appeal to less traditional manga readers, the Viz Media translation of Hot Gimmick gives everyone vaguely Valley Girl speech patterns. While this sounds reasonable coming from the mouth of the teenage protagonist, coming from traditionalist middle-aged Japanese housewives? Not so much.
DiC and Cloverway who licensed the Sailor Moon dub at separate times were Mis-blamed for what was actually the actions of the sub-contracted dubbing company Optimum, who was responsible for most of the slang, as part of their marketing was based on the fact that they would add "correct" slang and cultural references. (DiC could arguably have sued them for false advertising.) It's also why the practice continued with Cloverway. Take for example this line from DiC's Sailor Moon dub:
Serena: This contest is going to be major boss, Luna!
This leads to wrong, wrong characterization. Michiru, Haruka, and Setsuna are characters who would never use slang in the Japanese version, but here they are saying "Hey girlfriend!" and "You look like the bomb in those kimonos!" By the way, the above got poked fun at in this fanart.◊
Though by the mid 2010s, saying that someone looked "bomb" was accurate, though it fell out of favor fairly quickly (and omitted the "the").
Several other examples, like "Wicked cool," "the bomb", etc. "Hunkasaur" was used to describe a cute guy several times.
"But Rini, I thought you said he was fly!"
Lampooned in Sailor Moon Abridged where Sailor Venus' debut is filled with hackneyed Valley Girl speech. "Okie dokie pokie!"
The Abridged Series also lampshades this by having the characters say the lines exactly as they are in the dub.
Also from the Garlic Jr. arc: "Totally crampin' my style!" or "What a bummer!"
Z has other examples as well, even in the superior re-dubbing of the first 60-some episodes - though they usually aren't quite as bad as the above. Krillin is the usual culprit, having actually said "totally radical" at least once, and describing Goku as "one bad dude".
In one episode of the early Funimation dub, after it was explained to him by Vegeta, Krillin describes the Healing Vat that he put Goku inside of as "mondo cool". Vegeta even repeats it in his head while he's thinking of his plan to kill the three heroes after he kills Frieza.
Yamcha: "Vegeta was crying? THAT'S WACK!"
The narrator says the trope name word-for-word in the first episode of the Funimation Dragon Ball dub.
Excel♡Saga had an episode where Excel and Hyatt had to be the teacher of a bunch of Delinquents who spoke in incredibly anachronistic slang. However, this was both in the original and intentional, as Hyatt actually questioned why they were talking like that.
Parodied in the 4Kids dub of an early episode, when Jessie and James disguise themselves as teenage Valley Girls who talk exclusively in over-the-top Totally Radical speak. The original Japanese version is making fun of the ganguro fashion fad, wherein Japanese girls bleach their hair, tan their skin, and wear lots and lots of DayGlo eyeliner and lip gloss - all of which makes them look like a cross between the stereotypical California Surfer/Valley Girl and some sort of monstrous crone. Not surprisingly, this is also parodied with Jynx, which is also modeled off of the Yama Uba (Mountain Hag). It even gets Lampshaded:
Ash: Do you know anyone who even says "radical" anymore?
Misty: Mm-mm.
Brawly in the 4Kids dub (though it makes sense given that he's a Surfer Dude), and a one-shot DP character named Sho, who the TPCI dub made into a Jive Turkey turned up to eleven, speak like this.
4kids and especially TPCi use a lot of outdated and/or awkward slang in the English dub. Lines include: Ash's "Raise the roof", Brock saying his Poké Balls were "on the blink", Ash referring to things as "psyched", Jessie's "There's nothing worse than getting your head handed to you by a homie", Ash's "I'm no noob", and Meowth's "Dig it".
Chrono Crusade (the English dub at least) uses slang from the 1920's such as "Jake" instead of "cool" or "fine". Justified, though, because the setting is New York City in 1928.
There is Nunally's in one of the dubbed Code Geass Picture Dramas: when trying to talk like a boy (it was the Crossdressing Festival), she comes up with "Radical, dudes!". Between her attempt at a masculine voice and the picture accompanying it, it came off as adorable rather than annoying.
Elemental Hero Neos: If you go into this duel doubting yourself, Yubel will own you!
Yuma, main character of Yu-Gi-Oh! ZEXAL has his own arsenal of awfully (or perhaps awesomely) corny phrases. As dubbed in English, they include "Time to high-five the sky", "Get set to get decked", and "I'm feelin' the flow!" His optimistic lingo tends to irritate others at first, then work its way into their hearts. This is, as you might expect, a dub addition, but a very unusual one: in the original, he had one catchphrase, the made-up word "Kattobingu." The dub cycling through various slang terms is halfway between applying this trope and trying to find some kind of equivalent to a word that doesn't exist.
Rad, of Transformers: Armada is infamous for his catchphrase "Wicked sweet!", as well as the meme "I want to tell you about the Transformers!"... and, well, just look at his name.
The infamous 4kids dub of One Piece changed the original Japanese opening (which they even had translated) into a rap song. A very bad rap song.
The Negima! Magister Negi Magi manga has this problem in a few volumes, depending on who's doing the translation. The first volume practically borders on a Gag Dub. Volume 5 is a little better, but having characters actually say "OMG" and "WTF" does not work well.
In the .hack//SIGN DVD exclusive episode "Unison," there is a lovely conversation between Balmung, who is an office worker in the real world, and Kite.
Balmung: This shindig looks like the bomb-diggity. Kite: What did you say? Balmung: What I mean is, it's not bad at all.
Lampshaded/discussed in Bleach when Ganju, Ichigo, and Hanataro argue about whether certain slang is still current. This raises interesting questions, since Ganju and Hanataro live in a world resembling Feudal Japan. That said, Ganju is the leader of the local equivalent to a motorcycle gang, so whatever.
The dub of Inuyasha kept throwing ridiculous slang into Inuyasha's dialogue. He's grown up in feudal Japan, but he keeps saying things like "Hella Nasty."
Considering that High School is in the title, the English dub of High School D×D has this with everyone, although a little more modern. Compare the two versions:
Jap Issei:[after the girls claim that Kiba will be sullied by Issei's presence] Damn, cut the BS, will you?
Dub Issei:[same scene] Settle down will you? I promise not to steal his pimp juice.
America:Dude, I'm like, the first one here~! Now when everyone else shows up I can go, 'Aren't you a little late?'[Beat] They're gonna feel, like, totally ridiculous, yo!
Denmark in the dub is a milder version of this; he's the only one of the Nordics to throw "yo," "Holmes," and "fo' sho'" in his dialogue.
Valt from Beyblade Burst is prone to using 90s slang like "wicked" and "totally" in the English dub. He also mixes this with more modern slang, such as at least once calling his friends "peeps". In this case, however, it fits Valt's personality.
Speaking of Beyblade, the Nelvana dub of Bakuten Shoot Beyblade is peppered with characters spouting 90's-early 2000's slang. As the dub went on, however, the characters stopped using those terms and/or used them less frequently.
In one Yo-kai Watch episode, the Kappa start acting like rappers. This is lampshaded when Whisper calls Kappa outdated and pathetic for trying to be a DJ and says that people don't even wear backwards hats anymore.
Played for Laughs in Kaguya-sama: Love Is War, where the school's cheer team consists entirely of overly energetic types who speak in such heavy slang that it's practically a foreign language. After just one club meeting, it rubs off on snarky loner Yu Ishigami:
Ishigami: Shinomiya-sempai, you're dope AF. Kaguya: What does that mean? Ishigami: I don't know either...
Powerpuff Girls Z: Not too much in the way of speaking, but most of their motions seem ripped from '90s "thug4lyfe" gangsta rap videos.
The English dub of Puella Magi Madoka Magica occasionally gives Sayaka Valley Girl-inspired slang like "As if!" and "For realz!" particularly in the early episodes before the show's true nature is revealed. Though it's most out-of-place in Episode 6, where she dramatically describes her fight with Kyoko as "a bona fide battle to the death, for realz."
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