The Philanthropist Point Shop is located in the Silph Co in Saffron City. In particular, Inside you can obtain these items after talking to the NPC:

Items PP Needed
Choice Scarf 6,000
Choice Band 6,000
Choice Specs 6,000
Angel Wings 7,500
Halo 10,000
Ancient Key (Tooth Half) 15,000
Amie Stone 30,000
Crown 100,000

You can obtain PP in many various ways. Some include:

Altar blessing: You can get PP by donating to the Altar Blessing in Vermillion city. $1,000=1PP; 1 Credit = $1,500

Various blessings (World, Christmas, Drop, Halloween): Use these blessings every hour. You get 500 max if there are more than 500 people on currently. If there are less than 500 people on, then you get the PP according to the number of people on (For example, if there are 430 people on, you get 430 PP.). These are located in the credit shop.

Item Bomb- You can also get PP from setting off item bombs. You get 1200 PP as a base, plus additional PP for the number of people on. So if you have 700 people on its 1200 PP (base) plus 700 people, resulting in 1900 PP. These are located in the credit shop.