The Pirate Gooms and D.D.s from the early titles are very memorable to me. I also like that weird bird-bat-pig thing from 4, as well as the robotic bird. Looks pretty cool for an enemy that dies when Wario bumps into it!
I'm also very amused by...
This fascinated me enough to dig a little deeper, with how much it doesn't sound like a track Nintendo would ever approve of for any game, let alone Wario... but all I've found is a separate upload from around the same year (albeit some months...
According to an old revision on The Cutting Room Floor Wiki, a vaguely Mario esque song was originally present on the official site for Wario Land: Shake It under the name 'Plumber's Cave':
https://tcrf.net/Wario_Land:_Shake_It!
I posted this...