Also, they not only are +2, but they naturally have priority over anything because they are items; so that is crucial in some fights where you'd get outsped and wiped off, you get your +2 off before their attack. This means they are definitely better than moves like Nasty plot or such. Because they don't occupy a move slot and they have priority against anything.
Also, money doesn't really matter since you can just grind 5k at a time on the circus trainer "challenge" and X items are only 350 to 600 I think.
Use a X-Special Def/X-Def depending on the moveset of the gym leader's first poke, then keep setting up your speed and attack to wipe their team.This might not be the prettiest way to do it, but is definitely a better option than grinding an entire team just for 1 battle.
The main reason I opened this thread was because of all the advice threads I saw around with several posts reccommending strategies/movesets that would take a long time to achieve just for 1 fight. Maybe the best advice is to buff up your stats with these OP items.
Still, I might be wrong, as I said this is just what worked for me; might be different from another perspective