The free Gallery caps at 100 cards, so if you were creating, say, a 250-card custom Limited set, expanding that option could be useful
Espathra ex's ability makes the attacks of the opponent's active Pokmon cost one extra energy to use, meaning that players can sometimes be delayed for a turn because they are unable to attack
This allows players to take down benched Pokmon with the power of the six damage counters that are placed by Dragapult ex's Phantom Dive attack
The downside is that you then have to discard three cards, but the kinds of huge creatures you can pitch to this in green often have double that power
The Castle usally ETBs tapped, so you'll take a turn off
While this isnt as efficient as bringing them back to the battlefield, it does mean you get any cast triggers you need, along with ensuring you dont have to sacrifice anything along the way either