Pokémon Brilliant Diamond and Shining Pearl bring back the challenging Gym Leaders of the Sinnoh region, including Candice and her ice Gym in Snowpoint City — and if you’re not careful, you could get completely stuck inside.
As Pokémon analyst @eclipse_tt displayed on Twitter, it’s possible to get trapped among the snowballs at the center of the Snowpoint City Gym. You can’t push them aside once you’re down there, forcing you to start from an earlier save. Fortunately, avoiding the fall isn’t too difficult: be extra cautious around the stairs in the center of the room. Make sure you have a backup save before entering the Gym, too, as an extra precaution. You definitely don’t have to lose all your hard-earned progress.
Eclipse’s thread also details a speedrunning technique: it’s possible to slip and slide your way right past all those snowballs and hills and go right up to Candice herself. Attempting this may result in the softlock mentioned above, so be warned. If you’ve already conquered the Snowpoint City Gym, you can always rematch the Gym Leader here too.
If you want your own ice-type Pokémon, you can evolve Eevee into Glaceon. That’s one of many special evolutions in Brilliant Diamond and Shining Pearl. The list includes changes like Clefairy into Clefable, Nosepass into Probopass, and more.