Pocket Pikachu
Nintendo released two versions of the Pokémon Pikachu which was also known as the Pocket Pikachu. The virtual pet differed from all of the other virtual pets at the time in that it wasn’t focused on feeding your pets to keep them alive and instead focused on getting people to exercise by walking and tracking steps with the built in pedometer.
The second release, Pocket Pikachu Color (aka Pokémon Pikachu 2 GS in the US release), is available in clear and silver casing with a colour display featuring more animations. The second release was also compatible with the Gameboy Color games and could be connected with Gold and Silver via the device’s infrared port to exchange mystery gifts.
Oddly enough there were other versions of the Nintendo made device for other brands including the Pocket Sakura and also Pocket Hello Kitty. As Sega and Nintendo were still rivals at the time, the Sakura device was published under Media Factory.
Pokewalker
The Pocket Pikachu Devices eventually inspired the Pokewalker devices released alongside the remakes of Gold and Silver, HeartGold and SoulSilver. Pokemon could be taken from the game and then put onto the device and walked for additional ingame feature tie ins.
This page also has a lot of interesting technical analysis and information on the programming and hardware of the Pokewalker as well. He also has an application for PalmOS that can interface with the Pokewalker as well.
Manaphy No Tamago
A Manaphy themed virtual pet was released by Tomy alongisde the Pokemon Ranger Game.
Here’s a review of the device and its features
Eevee x Tamagotchi
In 2019 there was also a collaboration between Bandai and Nintendo and they released a tamagotchi inspired virtual pet. They released the Eevee x Tamagotchi virtual pets in Yellow or Pink.

Eevee evolution chart for the virtual pet.

The Bandai collaboration came in two colours, yellow and pink.