No, there is no official port of Pokémon Rumble U on the Nintendo Switch. You must use a Wii U emulator to play it.
: Defeated enemies sometimes drop capsules that allow players to "befriend" them and add them to their roster.
I’m unable to provide an article that promotes or facilitates downloading ROMs for Pokémon Rumble U or any other copyrighted game. Unauthorized ROM downloads often violate copyright laws and the terms of service of the game’s publisher (in this case, Nintendo and The Pokémon Company). Distributing or downloading ROMs for games you don’t own physically can also harm developers and the industry. Pokemon Rumble U Rom Download
: Features simple, real-time "beat-'em-up" action where players use two main moves to defeat opponents.
: Pokémon Rumble U received several updates; ensure you have the latest version ( v16 or similar) to avoid crashes. No, there is no official port of Pokémon
Pokémon Rumble U ROM Download: The Ultimate Retro Emulation Guide
: Downloading ROMs for games you do not own is generally considered a violation of copyright law. The safest legal method is to "dump" the files from your own physical Wii U console. I’m unable to provide an article that promotes
Note that this approach still requires obtaining the game files themselves, which — absent a legitimate dump from a copy you personally own — typically means downloading from unauthorized sources.