This section covers cards with effects that switch in one of your opponent's Benched Pokémon, or less commonly switch out your opponent's Active Pokémon.
What are some uses for switch-ins?
You can switch in a Basic or Stage 1 and KO it before it evolves.
If you have an attack that damages both the opponent's Active and Benched Pokémon unevenly, you can switch in/out better targets. For example, Wellspring Mask Ogerpon ex's Torrential Pump does 100 damage to the opponent's Active and 120 to one of their Benched, so if your opponent has a 110 HP Pokémon Active, it will survive. You'd want to switch it out so it can be KOed by the Bench spread instead.
You can switch in an opposing Pokémon can't attack or retreat in order to stall.
If your opponent has a Pokémon with a damage prevention Ability that makes it immune to your current attacker, you can switch in a different target to keep up your offense.
If your opponent has an Ability-locking Pokémon that only works while it's Active, you can switch in something else to release the lock.
If you're down to 2 Prizes, but your opponent's current Active Pokémon is a 1-Prizer or has too much HP for you to 1HKO, you can switch in a weak 2-Prizer from their Bench and KO that instead. (Succinctly known as "Boss for game".)
The default forced switch-in card. Its power is tempered by being a Supporter, meaning you can't play other draw/search Supporters on the same turn. Some decks will have Abilities to compensate, other decks will save Boss as the last play they make.
A nerfed Pow! Hand Extension (and thank god for that). It's an Item, but you have to be behind in Prizes to use it.
Like Iono, it's playable in slower decks that don't mind giving up early Prizes.
A powerful forced switch-in whose only drawback is being an ACE SPEC. Switching out your own Active can be an annoyance if it's your only attacker, but you can use another switch/free retreat/Scoop Up effect to bring it back in.
The ACE SPEC of choice for Raging Bolt ex and Joltik Box.
Unlike the other cards here, Iron Bundle is a switch-out, which is worse than a switch-in since your opponent gets to choose what to bring in. Sometimes though, you just want the opponent's Active out of there, and would settle for any of their Benched Pokémon coming in.
Being a Pokémon, Iron Bundle is easier to search for (Nest Ball, Artazon) and reuse (Night Stretcher, Super Rod) than the Trainer switch-ins.
A forced switch-in, balanced by failing on tails instead of being printed as a Supporter.
Played in low setup, Basic-only decks that can cycle through their decks quickly, giving them multiple chances to hit heads on at least one Pokémon Catcher.
Part of the Team Rocket's engine.
Team Rocket's Mimikyu acts as a pivot to retreat back to Team Rocket's Mewtwo ex for free.