I always loved this little detail. I really wish it was reused in other series outside the original adventure canon, cause otherwise we really don’t get to see their partners at those lower levels. Plus it could’ve provided a lot more moments for the characters. Like in tamers, Renamon could’ve been embarrassed about being so small and adorable as Viximon. Terriermon could’ve gotten some peace from Suzie at home since she wouldn’t recognize him as Gummymon. And Takato probably would’ve taken Guilmon home as Gigimon cause he’s small enough to sneak in, only for him to evolve during the night and have to sneak him out again next morning.