Species names.
Why are some English species names so different from the Japanese? Most changes are unnecessary and some don't make sense.

>Blastoise
JP Shell Pokemon > ENG Shellfish Pokemon

>Rhyhorn
JP Spiky Pokemon > ENG Spikes Pokemon

>Sceptile
JP Jungle Pokemon > ENG Forest Pokemon

>Corphish and Crawdaunt
JP Rouge Pokemon > ENG Ruffian Pokemo
JP Ruffian Pokemon > ENG Rouge Pokemon

>Dialga
JP Time Pokemon > ENG Temporal Pokemon

>Swanna
JP Swan Pokemon > ENG White Bird Pokemon

>Eelektross
JP Electric Fish Pokemon > ENG Elefish Pokemon

>Froakie
JP Foam Frog Pokemon > Bubble Frog Pokemon

>Pancham
JP Naughty Pokemon > ENG Playful Pokemon