Offensive Moves: Absorb, Drain Punch, Draining Kiss, Dream Eater, Giga Drain, Horn Leech, Leech Life, Mega Drain, Oblivion Wing, Parabolic Charge, Strength Sap.
These all heal 30% more HP to the user with Big Root held.
Status Moves: Leech Seed, Aqua Ring, Ingrain.
These all restore 30% more HP per turn when active with the Big Root held.
Abilities: Liquid Ooze
With Big Root held, the holder takes 30% more damage from Liquid Ooze.
Hope this helped!