If so, could I use the Pokemon and items obtained in competetive play.
Yes, as long as the moves, abilities, and EVs you gave them were legal, you could use them in places like the WiFi room.
How to change your username How to add a user avatar Why was my post hidden? Question etiquette Flags vs Downvotes Anime FAQ Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.