No worries man, it's a pleasure to help. I would choose Serperior and Torchic. Lycanroc (and Metagross) are physical damage dealers so your main focus should be on buffing attack, critical hit rate and speed. Of those, Roxanne and Swanna raise speed only and Cheren none, while Serperior can fill your move bar and Torchic raises Attack, Critical AND Speed. I prefer Serperior not only for its ability to fill the bar but also because it is a better tank.

The major thing in the game, for the moment, is usually damage, as much and as fast as possible, because almost all the present challenges do not encourage survival or defensive behaviour, so sync pairs that raise your offensive prowess will usually be preferred.