I charge all my iPads large and small and iPhones with this device.
But I don't know exactly what 25 watts means. I would be careful with laptops.

I'm not quite sure if I understand your question correctly. I have charged devices with (according to the display) less than one watt and also my company laptop with around 60 watts.
Charging the powerbank depends on your charger. I don't know the lower limit, but I have charged it with only around 10 watts (it just takes a long time).
My mobile phone charger usually charges the powerbank with around 15-20 watts. I don't think 25 should be a problem.