April 1, 2007 was an April Fool's Day that fell on a Sunday.

Hoaxes

Sunain announced her departure^[1] from #pocketmonsters and the community in general on March 26, then returned on April 1 itself.
#pocketmonsters also released a fake episode of School Rumble falsely labelled as a subtitled DP024.
Pokecharms.com was taken down impending action over the Copyright Infringements taking place on domain: Pokecharms.com under a claim by Plaintiff: Nintendo United Kingdom; relating to the franchise: Pokémon.
Pokemopolis announced and effected a merger with Serebii.net.
Legendary Pokémon announced and effected a merger with Serebii.net.
Pokemon.Marriland.com claimed to have unearthed information about the third game in the Generation IV series, which they called Pokémon Zircon. [2]

Meta-hoax

Serebii.net revealed a number of English names for Pokémon Diamond and Pearl towns, attacks, abilities and items, which many incorrectly believed to be a hoax.

Bulbagarden forums became Bananagarden, then a mock civil war broke out between the League of Neutral Posters led by Evil Figment, and the rest of the staff and members led by Pie.
SPPf removed all avatars and custom user titles due to "server errors". Some forums were also deleted.
Dogasu's Backpack was changed to Satoshi's Orenospace (a play on MySpace) page. Pages for Takeshi and Harley were also created.