A triggered ability is a triggered ability. There's no "active"/"passive"/whatever distinction.
A triggered ability will trigger whenever the appropriate event happens. Whenever you gain life for any reason, including as a result of Soul Warden 's own triggered ability, Ajani's Pridemate will trigger.
Did I answer the right question? Your post is a little unclear.
October 10, 2014 10:04 a.m.
And yes it will. Soul Warden 's ability triggers when a creature enters the battlefield. So Ajani's Pridemate will be on the field when the ability goes on the stack. Soul Warden 's ability resolves and you gain 1 life. Ajani's Pridemate 's ability then triggers and goes on the stack.