What are some good moves to use on this guy that take advantage

>>26820996
If you're going for a special set, I recommend:
Charge Beam
Icy Wind just to lower speed
Ancient Power for them boosts
Flash Cannon/Psyshock for stab
You could also throw on U-Turn.

It's a good stealth rock setter.

>>26820996
Shadow Ball gets a 40% chance of lowering spdef

>>26821059
>>26821106
Neat. Guess I'll go Psyshock/Flashcannon/Shadowball/Charge beam.

Maybe I'll put a life orb on him too.

>>26821128
Life Orb is bad on any Jirachi set, it's a Pokemon you don't want to be worn down too much regardless of its role.
Either way special Jirachi is pretty underwhelming compared to physical one. Iron Head + elemental punches provide solid coverage and plenty of opportunities to hax your opponent. You can even drop one elemental punch for Drain Punch if you need a lure for certain Dark types such as Bisharp. Goes well with Scarf, Band, Expert Belt or even Colbur Berry.
Another annoying set is SubToxic with Iron Head and Fire Punch as your attacking moves and Leftovers for passive recovery. Flinches + Toxic will obliterate even the sturdiest physical walls, as long as they can be poisoned.

>>26821128
An Assault Vest would be better. As your spamming Charge Beam to grab boosts and Jirachi is running nothing but offensive moves. Putting it on a timer isn't a good idea when Jirachi wont outspeed much.

Meteor Mash has a 40% chance of boosting its Attack. A Calm Mind/Thunder Wave/Rest/Snore set could be used if you're desperate for a unique set. Charge Beam is hard to justify over Calm Mind, and Togekiss does the Ancient Power boosting thing better.