The sky's the limit with new strategies in the Pokémon TCG: XY—Roaring Skies expansion. Take a look at some of the tactics you can employ in your next winning deck.
Major Bench Damage with Shedinja and Mega Gallade-EX
Set Mega Gallade-EX (35/108) up to do serious damage to your opponent's entire party with help from Shedinja (11/108). For one Grass Energy, Shedinja will put a damage counter on each of your opponent's Pokémon with its Cursed Rain attack and then switch back to your Bench—which means Mega Gallade-EX, with its 220 HP, can move up to take your opponent's attack. When it's Mega Gallade-EX's turn to attack, its Unwavering Blade attack will hit with full force, doing 110 damage to the opponent's Active Pokémon plus 30 damage to each Benched Pokémon with a damage counter on it.
One major concern with this setup is that with only 30 HP, Shedinja is pretty weak, so you'll want to set up Mega Gallade-EX as quickly as possible. You'll certainly want to include the Gallade Spirit Link (83/108) Tool card in your deck so your turn doesn't end when you Mega Evolve. After that, you might want to consider switching to the Wide Lens (95/108) Tool card, which might increase the damage you can do to your opponent's Benched Pokémon, depending on their types. You'll need a little help to make that switch: the Xerosic (XY—Phantom Forces, 110/119) Supporter card can be used to discard a Pokémon Tool card from either your or your opponent's Pokémon.
Sky Field Tactics
The Sky Field (89/108) Stadium card has all kinds of potential for changing the entire landscape of your game. Take a look at a few ways you can use it to your advantage.
The combination of Mega Rayquaza-EX (76/108) and Sky Field is pretty clear—the more Pokémon you can put on your Bench, the stronger the Emerald Break attack becomes. Consider including Winona (96/108), who lets you get up to three Colorless-type Pokémon out of your deck. If you go this route, definitely include at least one Shaymin-EX (77/108) to help refill your hand after you've put all those Pokémon on your Bench. (But watch out if your opponent is running Exeggutor (2/108): its Shake It Off attack does damage based on the number of Colorless-type Pokémon the opponent has in play.) Another option to fill out your Bench is Carbink (47/108), a Fairy-type Pokémon whose Jewel Armor Ability prevents it from taking any damage while it's on your Bench. It can just sit there safely while Mega Rayquaza-EX continues to hammer away.
Another valuable card for use with Sky Field is Altaria (53/108), whose Song of Echoes attack lets you shuffle your hand into your deck and then draw cards equal to the total number of Benched Pokémon. With Sky Field and a full Bench, you could draw 8 cards entirely on your own...and you could get as many as 16 if your opponent's Bench is also full. That's more than a quarter of your whole deck at your disposal! And if your opponent tries the same trick? Bring up Salamence (57/108), whose Power Howl attack does 20 damage times the number of cards in your opponent's hand.