Reserving arenas (basics and use in strategy). I have no idea how long this should be, but I will start writing soon.
EDIT: I should probably have enough time in ASB to be considered "experienced," whatever that means.
Aside from the Pokémon, arenas are the single most important part of any ASB battle. From the generic Indigo Stadium to Nuclear Missile Silos to the open ocean, every type of arena is playable in ASB. Every arena can always be used to your advantage, but there are always a few general things to think about in every arena. The first is the most simple: terrain. Is there water, or is it entirely dry? If it has any water, most water attacks can be employed, and water Pokémon are at a distinct advantage. If not, the opposite is true. Even more subtle things, such as sand and grass, can also be tossed in the air or lit on fire, respectively, changing the pace of the battle. The second major thing to be considered is weather. While it isn’t quite as powerful as it is in competitive play, only a fool would dare to ignore its power. If it is permanently raining, water Pokémon will be that much more powerful, while Fire types are going to have a tough time. Sun, Sand, and even Hail can also potentially make a seemingly impossible situation winnable. This is important, as arenas very frequently have some sort of permanent weather, and it should always be considered when designing an arena to aid your Pokémon.
The third major thing to consider is the evasiveness allowed by the arena. While Indigo Stadium may not offer much cover, a rocky field or dark cave offers plenty of options for hiding, allowing certain death to be avoided in some cases, and even forcing the opponent into being unable to attack at times. So, now that you know about arenas, it’s time to touch on making the most of them. The challenger of a battle should always build the arena around his Pokémon. If his Pokémon are all fast, frail fire types, he may want to seriously consider a rocky field in the sun to provide for evasive actions and a boost to fire moves. If one wants to use an aquatic Pokémon, a pool in the arena is almost necessary. While a Pokémon can be powerful in its own right, and a strategy can be amazing without abusing an arena, the best players will always keep the arena in mind, and constantly be aware of how it is working for and against them.