@NightOfYuyuko
Okay, so we are heading into a new format, which means exactly what decks will be good is open to debate. A lot of us expect
Garbodor... oh, I should probably explain that.
Garbodor (
XY: BREAKpoint 57/122)
also has the Garbotoxin Ability you should remember from its predecessor. Without a good way of discarding Pokémon Tools, this could lead to a metagame split between Ability, Ability lock, and the handful of decks that aren't bothering with either.
Greninja BREAK decks lose a little from rotation, but probably keep enough to keep going on.
Personally I recommend easing back into the game; focus on Pre-Releases and League. I say this because it will help you avoid over committing to anything, as reduce the risk of burnout. I've had friends try to get back into the game, going full tilt, and they ended up crashing and burning because they tried to
instantly become competitive their first season back. This way you'll reduce your stress from the game, letting you actually enjoy it, and if you don't then you haven't dumped a few hundred dollars into a hobby that you're going to abandon again right away.
Oh, and the Championship Series of tournaments (the ones that end with Worlds) use
both Expanded and Standard; single day events use one or the other (sometime mandate from above, sometimes at the organizer's discretion), while I believe two day events have the option of splitting (Day 1 Standard, Day 2 Expanded).