Credit goes to Burritokitten

One of Isabelle's best quirks is that she's capable of being nice to the enemy, only to steal them of their treasure and valuables, much to the New Balloon Otters annoyance when they hear treasure clanging inside her diaper. Many of her crewmates do this as it's a good way to keep treasure hidden, she only wishes she could do something about the clanging so she wouldn't look nervous when trying to leave. Her younger brother Edward can probably pull it off.
This is also why she buys thick poofy diapers as she hopes the thick padding dampens the sound the treasure makes.

End

Isabelle belongs to Me
Floatzel belongs to Game Freak