3 things needed for easy poo (I learnt from a Dr.):
1. fibre (not excessively, which will in turn cause constipation)
2. water (drink sufficient water)
3. oil (include a little healthy oil such as olive oil in diet, acts as lubricant for poo)
As for fruits, the best fruit that works for my boy and many others is PRUNES.
I give my boy 2 organic prunes daily and he poos easily.
On the day he doesn't eat prunes, he'd miss 1-2 days of poo.
Other poo-inducing fruits are papayas, peaches, plums and pears. Still, prunes work the best for many kids.
Avoid giving cooked apples and unripe bananas as these would cause constipation too.
All the best!