Well, just like with "Choose it or Lose It!" either 4kids, Cartoon Network, or PUSA went in and edited the title screen to change it from "Hooked on Onyx" to "Hooked on Onix"
The writers took quite a few liberties in this episode...
1. Why did they need to find a river when they had a Mudkip that could use water gun RIGHT THERE?
2. Why did Pikachu and Corphish run from 3 Geodude? Pikachu fried Brock's back in Kanto, and Corphish can use Bubblebeam, which is super effective.
3. If Pikachu and Corphish couldn't fight 3 Geodude, how could they fight a whole swarm of Beedril?
4. Why was the whole group scared of the Graveler and Golem? Sure, they look big, but Corphish knows Bubblebeam, Squirtle knows Bubble, and Munchlax knows Solar Beam. All super effective attacks! Plus, Pikachu fried a Geodude back in Kanto, so why couldn't it battle a few Graveler or Golem and do the same thing, 400 episodes later?