This section covers cards with effects that switch in one of your opponent's Benched Pokémon, or switch out your opponent's Defending Pokémon.
What are some uses for switch-ins/outs?
You can switch in a valuable target from your opponent's Bench and KO it. Some examples: weakened attackers, unevolved Basics that your opponent has already started committing Energy to, draw/search engines.
You can switch in an opposing Pokémon that doesn't have enough Energy to attack or retreat in order to stall. When you do this, you don't want to KO the Pokémon you dragged in, so you will usually use low damage or Bench-targeting attacks to keep that Pokémon alive and hindering your opponent.
You can switch out an opposing Pokémon that needs to be Active in order to use Cessation Crystal, or its Poké-Power (e.g. Jirachi).
You can switch out an opposing Pokémon to remove attack effects from it, e.g. Agility or Ice Barrier.
Switch-ins are unquestionably stronger since you get to choose what comes in, but have more strings attached to them than switch-outs.
Pow! Hand Extension is such an influential card, it has a section all to itself.
Same effect as the modern Pokémon Catcher.
It's unreliable, so usually only aggressive decks that can refill their hand quickly with draw Supporters will want it.
Hidden Power is unique: it effectively forces in Basic Pokémon from your opponent's hand, instead of existing ones on their Bench. This may remove the opportunity for your opponent to use them for their when-played Powers, or as Energy (for Holon's Pokémon).
You can harass those Basics that were Hidden Power-ed in at a later stage with Pow! Hand Extension.
A card with an aggressively-slanted switch-in attack. Flick Poison can wear down opposing Pokémon so that they're in range for 1HKOs later.
Reactive Aroma is trinket text.
The defensive counterpart to Roselia. Night Song inflicts Sleep instead of Poison, which is better if you want to buy turns not getting attacked, instead of setting up KOs later.
Plunder is a useful second attack, removing Cessation Crystal.
Darker Ring forces a switch-in upon Umbreon ex being played.
Nectar Pod is a repeatable switch-in Power, but only works on Stage 2s. Nevertheless, there are plenty of good targets if you have an attacker that can 1HKO them (likely with Weakness). Just look at any Pidgeot deck and realize you can force in either Pidgeot or the other Stage 2 that they're playing.
This is not a comprehensive list.
These are commonly used as Cessation Crystal counters.
Warp Point is more common, as it has utility as a switch card too.
Cyclone Energy cannot be Pushed Away by Stantler.