Data transfered from old iPad to a new iPad and iPhone; will a reset of the old iPad, wipe the data from the new devices?

Solution 1:

If you factory reset your iPad, you won't wipe the data from your other devices.

To give you some perspective, it would be counter intuitive if you lost your phone and remotely wiped your device only to have all your other devices wiped as well.

That being said.... don't have the expectation that your other devices are back ups of your data. While you will have access to your data in the case of losing a device, if you inadvertently delete your data (all your photos as an example) that change will propagate to all your other devices.

Solution 2:

Provided you transferred to to the new devices space and not iCloud space and when you factory reset don’t accidentally reset your iCloud storage your fine. Just be care because some apps like notes, photos, contacts could be stored through other means.