In the latest official blog post for Super Smash Bros. Ultimate, Nintendo focuses on the versatile Pokémon Stadium stage:
Today’s Stage
Pokémon Stadium
After ten years, it’s back! In addition to the basic stadium formation, the stage also switches between Fire, Water, Rock, and Grass variations. If you want to win on this stage, you’ll have to alter your strategy based on the current formation!
Source: Official Super Smash Bros. blog
Pokémon Blog 