Nodes are bosses in Final Fantasy X-2. There are three of them — Node A, Node B, and Node C — and they are fought along with Vegnagun's Leg. Although the player does not have to kill them to win the battle, they give large amounts of Experience and AP, much more than the Leg does on its own, and have a chance of dropping a Hero Drink, which is an item available from only them, and Shuyin. However, they have much more HP than the main boss, and can only be struck by specific attacks.
The Nodes are too far away to hit with most regular attacks, so one will have to use long range ones, such as a Gunner's attack or magic. The nodes change colors, and the color they are depends on what they do. Red Nodes use physical attacks, Green Nodes use defensive magic, and Yellow Nodes use offensive magic. The colors represent what type of damage they will be immune to. Red nodes are immune to physical damage, green nodes are immune to magical damage, and yellow nodes are immune to damage that doesn't fall into either of those categories.
Magic is not useful against the Nodes, because they have high Magic Defense, although Flare and Ultima still do some damage. It would be a better to use long range physical attacks, because the Nodes have low Defense. Gunners have some useful skills for racking up damage, such as Trigger Happy.
Another strategy is to use Yuna's and/or Paine's Mascot dressphere as the Moogle Beam and Cactling Gun ignore defense, and when combined with the Break Damage Limit, can inflict large amounts of damage.
If all three of the girls have a Key to Success accessory, use the Lady Luck's Double Items auto-ability, or pass through the red gate from the Treasure Hunt Garment Grid, it is possible to get eight Hero Drinks per Node defeated (up to a maximum of 24 from this one battle.)