The user lays roots that restore its HP on every turn. Because it's rooted, it can't switch out.
The user plants roots in the ground, allowing it to restore 1/16th of its max HP at the end of every turn. This roots the user firmly in place, preventing it from escaping (unless it holds a Smoke Ball or its Trainer uses an escape item) or switching out.
Even moves that switch the target out cannot force a Pokémon under the effect of Ingrain to switch out. However, moves that switch the user out switch a Pokémon out regardless of Ingrain; additionally, a Pokémon under the effect of Ingrain can be switched out when the game allows the player to switch before an opponent sends out their next Pokémon after their previous Pokémon fainted. The effects of Ingrain can be passed by Baton Pass.
A Pokémon under the effect of Ingrain can switch out if it holds a Shed Shell. Ingrain prevents the affected Pokémon from being switched out by the Red Card, but does not affect the Eject Button.
Ingrain causes the affected Pokémon to become grounded, and therefore susceptible to Ground-type moves; Spikes, Toxic Spikes, and Sticky Web (only relevant when a Pokémon is switched in via Baton Pass and obtains Ingrain); and terrain—regardless of whether it is Flying-type, has Levitate, holds an Air Balloon, or is under the effect of Magnet Rise or Telekinesis. Magnet Rise fails if used by a Pokémon under the effect of Ingrain; the move Telekinesis cannot affect a Pokémon under the effect of Ingrain.