I've done a lot of mountain walking and rock climbing in North Wales. I wouldn't walk up any of those hills without the following kit:
Map
Compass
Whistle
Torch & spare batteries
Plastic bivouac sac
First-aid kit
Food & flask of warm drink
Spare food you don't actually intend eating unless you're stuck
Waterproof cagoule & overtrousers
warm hat, gloves, trousers (not jeans), fleece
dependable boots (or trainers if you're experienced and don't mind wet feet)
Telephone change or a mobile
The ability to use all the above in the correct way
And I'd tell someone where I was going and when I should be back.

Cheers
Ray