Well, there's not a lot of information to work with, so I'll answer broadly.
For In-Game Use
I wouldn't bother EV training in-game teams. It's long, boring, and (to me at least) takes away from the experience of the games. You can EV train if you want to, but you don't need to because you should always be a level or two above your opponents and Lycanroc is already pretty powerful, and very fast.
For Competitive Use
If this is a Lycanroc that you plan to use in Battle Spot or for special tournaments, then you should EV train it. But, I would only recommend doing so if it has a good nature (Adamant for Lycanroc-Midday and either Adamant/Jolly for Lycanroc-Midnight). If it doesn't have a good nature, it can still work for you, but you'll be fighting with a handicap.
For the Battle Tree
Do it if you want to, but if you don't EV train you'll find the Super battles even more challenging than they already are. Natures don't matter as much in the Battle Tree as they do on Battle Spot, but it doesn't hurt to have the right ones.
I hope this helps!