If your going for a slow sweeper, or support set up(or both in my case):
trick room- nothing else would work better, mainly since most of the new pokemon are slower than magikarps
reflect/light screen/energy ball- depending on how your team works, you will either want set up(if you have faster sweepers, which means not using trick room, and having both walls) or energy ball if you want more type coverage. personally, energy ball is great to use.
shadow ball/focus blast/toxic/thunder wave- first two for sweep and type coverage, second two for set up.
I reccomend also trying to put in pain split if your are setting up, which could replace trick room if you are NOT going slow sweep.
good EV's depends on the role:
slow sweep: 252 Spc.Att/252 HP
fast sweep: 252 Spd/ 252 Spc.Att
set up 1 survive: 252 HP/ 128 def /124 spc defence
set up 2 speed: 252 Spd/ 252 HP
slow sweep and set up: use fast sweep as you can set up quick to use reflect ect. then sweep of any fast attackers, and use trick room before you die.
You can use any, personally, try making a team of slow sweepers, give him max in HP and special Attack, and watch as he blows up teams in an instand.
BUT! the reason I gave so much choice as it all depends on what he fights with, he is a support, main sweeper, slow at that. If you give him the time, he nearly matchs chandelure due to trick room, without trick room, hes Underused at best.