There are some changes made throughout the dubs of the various Pocket Monsters series that occur in just about every episode.  Since it would be redundant to mention these in every single comparison, I'll compile the major edits on this page for easy reference.

The edits listed on this page only applies to the main TV series.  Movies, specials, OVAs, and the compilation of episodes known as Pokémon Chronicles are often edited under different standards.

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Show Title
The Japanese TV show, video games, and most other paraphernalia go under the tile Pocket Monsters.  In America, the TV show, video games, and other paraphernalia go under the title Pokémon.

The logo for the Japanese version of the show, taken from "Mezase Pokemon Master."	The logo for the American version of the show, taken from "Pokémon Theme."

The reason cited for the change in the show's name is because the Japanese title closely resembles another series, Monster in My Pocket.  As such, one will not be able to find any official source use the Pocket Monsters name in any of the English-speaking territories.

Cold Openings
In the Japanese version, viewers would see the show's opening theme followed by the first half of the episode.  After a commercial break, the second half of the episode would play followed by a second commercial break.  Then, the show's ending theme would play.

The American version followed this same format, more or less, until 4Kids' fourth season.  Starting with "Johto League Champions," 4Kids fabricated a cold opening by moving the footage that played before the episode's title screen to the front of the episode.  This was most likely a network mandated change as every other show on Kids' WB! was switching over to using cold openings at the time.

The Japanese version would not start using cold openings in its broadcast until the Advanced Generation episode "Psychic vs. Ghost!  The Midnight Duel!?" ("Fear Factor Phony!").

Opening Theme
Unlike with most other anime dubs, the companies responsible for the English version of Pokémon do not create English versions of the original Japanese themes.  Instead, all-new songs are created.  Video from the Japanese openings is rearranged and mixed with recycled footage from the episodes in the season for the new, shorter English openings.  A lot of the footage from the Japanese openings is removed, and most of the footage that is used is shortened and/or sped up.  In addition, some of the footage used has paint edits.

This shot of Jouto's Gym Leaders, taken from "Born to be a Winner," is one of several scenes created specifically for the English version of that opening.	The unedited version of the Rocket-Dan scene from "Battle Frontier."  A few episodes after "Unbeatable" premiered, Manene was digitally painted away.

Below is a list of the opening themes used in the dub and the sources for the footage used in the American opening.

English Song	Video Source
"Pokémon Theme"	Mezase Pokemon Master, episode clips
"Pokémon World"	Rivals, episode clips
"Pokémon Johto"	OK!, episode clips
"Born to be a Winner"	Mezase Pokemon Master (Whiteberry Version), episode clips, new footage created specifically for the English version
"Believe in Me"	Mezase Pokemon Master (Whiteberry Version), Ready Go!, Maemuki Rocket-Dan, episode clips
"I Wanna be a Hero"	Advance Adventure, episode clips
"This Dream"	Challenger!!, episode clips
"Unbeatable"	Pokémon Symphonic Medley, Battle Frontier, episode clips
"Battle Frontier"	Spurt!, episode clips
"Diamond & Pearl"	Together, episode clips
"We Will Be Heroes"	Together, Kimi no Soba de ~Hikari no Theme~, episode clips

The Japanese opening themes all contain opening credits, but the English versions (with the exception of the opening theme to Pokémon DP Battle Dimension) do not.  In addition, the short blurb of text that basically describes the premise of the show (which started appearing in Mezase Pokemon Master (Whiteberry Version)) does not appear in the dub, either.

Starting with Together, the opening themes in Japan have had their animation updated whenever a main character's pokemon is captured, evolves, or leaves the group.  The animation in the equivalent scenes in the English version, however, do not.

Background Music
Both 4Kids and Pokémon USA (PUSA from here on out) mixes both the Japanese music and music created specifically for the dub in each episode.  As of the time of this writing, no single episode of the regular TV series has consisted of only Japanese music or only dub music; it's always been a mixture of both.

In an interview with Michael Haigney, he states that "We replace [the music] for both artistic and commercial reasons. I don't think it's any more or less insensitive than dubbing."  Norman Grossfeld, when talking about the first movie on its official website, states that "We also rescored the entire movie with all new music that would better reflect what American kids would respond to."

While the practice of mixing soundtracks in this manner is rare, it's not unheard of.  Other dubs that mix soundtracks include Zatch Bell, The Prince of Tennis, MÄR, Kiki's Delivery Service, the Fox Kids Escaflowne dub, Tokyo Pig, and Battle of the Planets.

Who's that Pokémon?
Amazingly enough, the English version of Pokémon retained the eyecatches from the original series, something that's virtually unheard of for made-for-TV dubs.  The layout was changed, however, to match the rest of the packaging for the show.

The Japanese eyecatch for the first episode.	The American equivalent

With Pokémon Advanced, 4Kids continues to use a "Who's That Pokémon?" eyecatch despite the fact that the Japanese version had switched over to one that doesn't change from episode to episode. 

In Pokémon Advanced Challenge, 4Kids got rid of the "Who's That Pokémon?" segment and replaced it with a new segment called "Trainer's Choice."  In "Trainer's Choice," a multiple choice question is asked before the commercial break and is then answered when the show returns.  Most of the questions ask which pokemon is the best choice to face off against a particular pokemon, but other questions will ask which pokemon evolves into which.  The Trainer's Choice has been shunned by fans because 4Kids would get the answer wrong about half the time, showing fans just how little they actually know about the franchise that they had been working on for the past eight years.

The most infamous Trainer's Choice eyecatch comes from "A Fan With A Plan," where 4Kids erroneously states that Arbok evolves into Seviper.

The Japanese version, however, continued to use the same eyecatches for the remainder of the series.

When PUSA took over control of the anime, eyecatches disappeared from the dub altogether.

To Be Continued
When PUSA picked up the show in Season 9, they started to lengthen the TO BE CONTINUED... screen in every episode by three seconds.  This was accomplished by freeze framing the final image of the episode and editing the music played at the end of the episode to make sure it continues playing for the extra three seconds.  Reasons for this edit are unknown.

To date, PUSA has made this edit in every episode that they've dubbed.

PokéRap / Pikachu's Jukebox / Pokémon Karaokemon
The music videos that appear at the end of every episode during the first few years of the series aren't present in the Japanese version.  The episode ends, the show cuts to a commercial break, and it returns with the ending credits. 

There is a pokemon rap in Japan, but it's a stand-alone song and isn't shown at the end of each episode.

Ending Credits
For the first season of Pokémon (before it began on Kids' WB!) and for whenever the show's aired on Cartoon Network, the show's ending sequence consisted of the credits running on one half of the screen and the video of the opening credits running on the other side as "Pokémon Theme" plays in the background.  When the show was picked up by Kids' WB!, the credits remained on the right side of the screen, but the left side contained commercials for other Kids' WB! shows.

Now that the show is on Cartoon Network permanently, the ending credits take up the full screen while an instrumental version of the opening theme plays.  There is no ending animation in the English version - there's only white text on a black background.

By contrast, the Japanese version has a separate song and animation for its end credits.  Also, as with all anime, the Japanese credits list each voice actor as well as the character he or she portrays; the American version simply lists the actors without telling who played what role.

As of this writing, there are a total of about 22 different ending themes (excluding remixes) throughout the various TV series.

Orchid-Hakase's Pokemon Lecture

After the end credits play, an approximately 30-second short known as Orchid-Hakase's Pokemon Lecture (or Orchid-Hakase's Big Encyclopedia, as it's known as after the start of Diamond & Pearl) plays.  During these shorts, Orchid-Hakase's computer chooses a pokemon who has already appeared in the anime for Orchid-Hakase to give a lecture on.  Once the pokemon's name is revealed, Orchid-Hakase gives viewers some information about it while clips from episodes in which the pokemon appear play.  After the pokemon being featured attacks Orchid-Hakase in his lab (usually because the professor does something to provoke it), a senryuu is written that works the pokemon's name in somehow.

The title screen for Orchid-Hakase's Pokemon Lecture.	Orchid-Hakase gives viewers some facts about the pokemon of the day.
The pokemon being featured usually end up attacking Orchid-Hakase after he does something stupid to provoke them.	At the end of the segment, Orchid-Hakase writes a senryuu with the pokemon's named worked in somehow.

The dub has never featured this segment, but footage from one of the segments was used for the opening portion of the VHS for Pokémon The First Movie.

Next Episode Preview
After the ending credits of each episode finish, Japanese viewers see a preview of the next episode while an instrumental version of one of the show's opening themes play in the background.  The previews feature clips from the next episode to give fans a taste of what's to come.

The preview screen used toward the end of Pocket Monsters Advanced Generation.

The American version does not have any previews, though the network airing the program may make episode-specific promos, usually during sweeps, to promote upcoming episodes.