What's your dicipline on children/teens/pets?

At the moment I have one toddler. Mom and dad use calm at first then firm if bad behavior continues. They haven't had to go beyond that yet and I'm reluctant to have them go to strict, but we'll see if it reaches that point. She has a lot of freedom to do whatever she wants, but no messes allowed outside of the two designated areas, no tantrums or meltdowns, and no splashing in the toilet. Messes and toilet splashing gets a firm response, tantrums get a calm response. She's a good girl for the most part or she's just committed to misbehaving in the three ways I mentioned. In which case I need to expand her imagination to find new ways to get into trouble.

I don't have pets in the household since they use up valuable slots.