From Bulbapedia, the community-driven Pokémon encyclopedia.
April 1, 2011 was an April Fools' Day that fell on a Friday. In the Pokémon fandom, many websites pulled hoaxes on gullible fans.
Bulbapedia as "Fushigipedia"
- Bulbapedia temporarily rechristened itself as Fushigipedia, "the Pocket Monster encyclopedia", complete with Generation I colors, references, and imagery of Pokémon throughout the site. The featured article was Game Boy, rewritten for 1998. To coincide with the Bulbasaur theme of Bulbapedia, the romanization derivation is taken from Bulbasaur's name, Fushigidane.
- Bulbanews temporarily undertook the name of Fushiginews updating articles "Every 13 years". Covering the front page were articles from 1998 including an article about a rumored Truck on the Vermilion City port.
- Bulbagarden forums were redesigned to become Retrogarden, with the forum taking on a look and theme of 1998 as though the announcement of Pokémon coming to the United States had just recently taken place.
- Bulbagarden Archives was given an aesthetic makeover and renamed Fushigi-Archives to match the themes of both Fushigipedia and Fushiginews.
Other fan sites
Pokécommunity vs. Serebii
- PKMN.NET reported on a new Pokémon Trading Card video game for the Nintendo 3DS titled "Pokémon Trading Card Revolution". 
- The PokéMasters temporarily renamed itself to "The Gary Oak Masters" and changed the themes of its main site and forums, disabling the style changing dropdowns on both. The forums also implemented a celebration of Gary Oak with every thread mentioning "Gary was Here" and the Rival music from Generation I being played. An account named "Gary Oak" was also created and used by the staff members to post messages reminiscent of Gary's anime incarnation. Additionally, the site posted a fake announcement of Pokémon Snap 3DS (a sequel to Pokémon Snap) with the first letter of each paragraph spelling APRILFOOLS and the source linking to Rebecca Black's 'Friday' video. April Fools' Day was on a Friday that year.
One of Psypoke's fake banner ads found on the site during April Fool's Day
- Psypoke was redesigned with an advertising campaign with the theme of Rebecca Black Version and Betty White Version. Advertisements were placed on the main site and forums with respective banners including Betty White Version RageCandyBar, Rebecca Black Xtransceiver and Frieda of Friday parodies, the latter being a reference to Black's song "Friday."
- veekun appeared as a mirror image, flipping back to normal when the cursor was over the page.
- Similar to previous years, PokéCommunity parodied Serebii Forums and locked the skin as the same Celebi green.
- PokéCharms was redesigned as Smug World Order (SWO) with a Smugleaf theming. The site announced its allegiance and dedication by handing over the site to "Lord Smugleaf". 
Pokémon Database as "Stunfisk Database"
- Smogon pretended to accidentally have deleted their whole Wi-Fi forum.
- Pokémon Database redesigned as the "Stunfisk Database", with Stunfisk taking the place of Scyther and Electivire in the header as well being tiled on the background.
- Marriland became "Scraggiland" for the day, complete with a new orange theme with Scraggy colors and Scraggy and Scrafty imagery. In addition, the site also introduced new themes based on Woobat, Vanillite, Stunfisk and Karrablast, with each theme also renaming the site after their respective Pokémon, although Marriland's new Scraggy avatar remained unchanged regardless of what theme was chosen.
- Pokébeach started a forum discussion called "Secret Soup". The banner of the forums had been distorted to slightly reveal a message. As the message was difficult to read, there was much confusion as to what was happening. The title of the thread was changed several times, including "Secret Soon" and "Secret Spam". Mods posted several comments about clues and such, and most of the forum got riled up with excitement and confusion. It was eventually revealed at the end of the night that it was all a prank.
- PKMNcast.com became distorted with images and signs of MissingNo. The banner had an image of MissingNo. on it, various parts of the website was missing, and the colors were changed.
North by Northwestern, a daily online newsmagazine at Northwestern University, was transformed into Meowth by Meowthwestern, with bogus Pokémon-themed campus news stories available in Blue and Red versions.