The best team is the one that compliments each other's weaknesses but since the game's difficulty is really not that hard, any team is acceptable as long your Pokémon's levels are high enough for the respective battles.
level x darkri
I would have to say rayquaza lv x
charizard g lv.x
In my opinion, the best party with move sets and EVs in Pokemon X including the legendaries is the trade and using of cheat codes such as AR.
They are not ' x Pokemon cards', if someone says ' oh i have a x Pokemon card!' they just have a LV. X Pokemon card.
and x
Lv 'X' is a Pokemon card level.Level 'X' does not exist in Pokemon games.
The Legendary Pokemon available in Pokemon X/Y are:Xerneas (X only)Yveltal (Y only)ArticunoZapdosMoltresMewtwoZygarde
the best is proboly arceus lvx
Double hit x scicor nightslash and faslswipe or slash
Metagross, Flygon :x in my opinion.
If you mean best i would recomend pokemon x and y or any of the rumble games.