This card confuses me a bit. Just to clarify...
For example:
If your opponent has 2 tools attached to their Pokemon, and and 1 stadium in play...
Relicanth can chose 1 opponent Pokemon, and deal 90 damage with "Grand Swell" ?
Correct.. it can Snipe anywhere for 90!!
Just don't get too excited when they're attaching Bench Shields... they will block Relicanth's damage if you target something with Bench Shield on it.