You choose which opponent, planeswalker, or battle the token is attacking as it enters.

The ability that defines Suki, Kyoshi Warrior's power works in all zones, not just the battlefield. As long as Suki is on the battlefield (and still a creature), that ability will count Suki herself.

Although the Ally token created by the triggered ability is attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example).