>>32343994I guess look at what's used, what other people are using etc.
A lot of teams use pairs of Pokémon that have a natural and obvious synergy, such as Pelipper+Golduck (Peliper has Drizzle which sets up Rain, Golduck has Swift Swim which doubles its speed in rain, and relatively powerful STAB Water, which is boosted in rain)
Other 'explicit' synergy like that are things like Torkoal and Oranguru; Oranguru sets up Trick Room while Torkoal protects, then Torkoal uses Eruption and Oranguru uses Instruct to make Torkoal erupt again.
As well as these, there's the synergy of having Pokémon who cover each other's weaknesses very well. There's a lot of cores people talk about like fire/water/grass, dragon/fairy/steel etc. which are meant to give great overall coverage, but it's really down to working out what screws over some of your team, and plugging a counter into your team.
Then there's a lot of Pokémon that just have all-round utility. Tapus and weather setters do a great job of this, since weather and terrain are abusable by a huge number of Pokémon. Speed Control (Tailwind, Trick Room, Electroweb etc.) are very important too.
In terms of the "state of the meta", you can get a good idea just from usage stats. Your team should have a solid answer to everything in the top 15 or so, and at least not suck against anything in the top 30.
http://www.trainertower.com/WCS-battle-spot-usage/ 
