I left them with 1 HP only because I discovered a pattern in her attacks. If I do remember correctly, she will use Hell's Judgement twice but will most probably not use any attack between this time gap. Or I had the luck to have Rinoa use Invincible Moon or used a Hero in someone.
EDIT:
It turns out I wasn't wrong after all:
The rest will only be used when Rinoa is in critical status by manually choosing the Combine command from the Limit Break menu. The player can't choose which attack Angelo uses, but the attacks Angelo uses depend on the Crisis Level.
■ Crisis Level 1: Angelo Cannon
■ Crisis Level 2: Angelo Strike
■ Crisis Level 3: Invincible Moon
■ Crisis Level 4: Wishing Star
So, what is Crisis Level?
Crisis Level is a hidden condition in Final Fantasy VIII used to determine how often a character's Limit Break will appear, as well as different damage outputs, additional statuses, and more options for the Limit Breaks. Crisis Level is achieved by having a character in critical status (having a character's HP lower than 32% of their max HP, though for Seifer, he must be lower than 84% of his max HP). There are four levels of Crisis Level, and aside from current HP, various statuses also factor into determining what a character's Crisis Level is.
So, for Rinoa to use Invincible Moon or Wishing Star, it would be best to have her HP really low. It seems Aura also helps.
Everything was taken from the FF wiki, btw.