These cut to the chase and let you damage your opponent's Benched Pokémon without having to use a forced switch-in/out card.
More often used for its Ability.
Dusclops has a similar Ability.
This card is an option for decks that are able to spread damage to the Bench. If you manage to get 70 damage on a Stage 1 ex or 90 damage on a Stage 2 ex, you could muster a 200+ damage attack to finish them off... or you could use Devolution instead, which will KO the Pokémon after its HP is reduced.
Note that devolving ex's this way into non-ex's only nets you 1 Prize for the KO.
Devolution can also generate some value against Stage 2s that were Rare Candied into. Your opponent would need to find another Rare Candy or Stage 1 to get their Stage 2 back. Conversely, if you know your opponent is playing TM: Devo, don't simply cease development after you get your Stage 2 attacker or Pidgeot ex out; try to also get a Stage 1 into play as a defensive countermeasure against it.
All Tera Pokémon are innately immune to damage from attacks while on the Bench.
If you're playing a deck with evolving Basics against a deck with Bench snipers, one strategy to beat them is overloading their snipers. Put down multiple evolving Basics with Buddy-Buddy Poffin and Artazon, so even if they snipe one, you can evolve the one that survived into a ex (using Rare Candy if it's a Stage 2) with enough HP to survive a snipe, and launch a counterattack from there.
Played in Stage 2 decks to protect the evolving Basics and Stage 1s.
Note that unlike the older Bench Barrier Ability, Flower Curtain does not protect all your Benched Pokémon. ex's are still vulnerable.
Unfortunately, Shaymin's HP is too high to search for with Buddy-Buddy Poffin.
Counters Munkidori by healing some of the damage that it's already bounced over, while also getting rid of its "ammo". However, Froslass can generate more.
Stops Dragapult ex's damage counter placement in addition to run-of-the-mill damage.
These counter Bench damage spreaders.
Ethan's Ho-Oh ex is questionable against the major spread damage decks, though. Its attack costs 4 Energy and fails to 2HKO Dragapult ex or Marnie's Grimmsnarl ex if they have Munkidori, and even faces the prospect of getting 1HKOed in return.