Very safe, and accommodates many of their needs. The pokémon naturally shrink down to fit inside, and improvements have been made to the design over the years with their safety in mind.

[The pokéball in Clavell's hand enlarged as he held it, just to the more 'normal' size than the shrunken state they all took on upon travel to make carrying them easier.]

Even larger. I can show you one that will still fit comfortably within this mall structure if you'd like an example? I have one even larger, but he is back at my home in Blossomcrown having a rest- and I don't think he would enjoy being in here.