Party Potions work the same as Party Buffs, once you activate one of these potions, all members of you party (within radar range) will get buffed with the potion.

Potion	Description
	[Party] Increase Defense Party Buff. Lasts 5 Minutes. Physical Defense +460 Magical Defense +138 Physical Evasion +200
	[Party] Increase Att. Pwr Party Buff. Lasts 5 Minutes. Physical Attack +115 Magical Attack +115 Deadly Attack +90
	[Party] Increase Att Spd Party Buff. Lasts 1 Minute Attack Speed +1.5 Movement Speed +1.5

How do You get those potions:

There are 2 Ways at this moment, you either get them in Free Rewards, or you get them in Tiered Spenders on the Web Item Mall