Appears I picked up Xcom2 at some point. Never played it.
I assume you mean no coop play? XCom2 did have a head-to-head multiplayer that was pretty fun.
In case you play (I've played a couple games recently):
1. Build GTS.
2. Train 3 snipers and a ranger. An ideal squad as Ranger/Snipers is 2 rangers and 4 snipers. 2/2, then 2/3 and 2/4 as possible. In basic game, personal compatibility and intelligence is not an issue, so any rookies will do. In WoC, high intelligence units with high compatibility are arranged in pairs, ranger-sniper, ranger-sniper and sniper-sniper.
As units will be damaged (and tired in WoC), fill-in units will be required, a couple rangers and a couple snipers, so keep building them after the A-team is assembled.
Shotgun modular upgrades (2 after first weapon class upgrade): Laser Sight and Auto-Loader.
Sniper rifle modular upgrades: Scope and Extended Magazine. I prefer hair-triggers instead of magazines early game, and instead of scopes late game. Early game one needs aim and late game one needs magazine capacity.
Keep the rangers camouflaged and the snipers on high ground behind them. The snipers can see the enemy because of the rangers (squad sight) but the enemies cannot see the snipers because they are too far away. The enemies can't see the rangers because they are camouflaged. The snipers are largely free to take shots without retribution or, often, even recognition of fire.
Research Officer Autopsy then Mech breakdown while building Proving Ground. Research Plated Armor (for the utility slot) while the Proving Ground does Bluescreen Protocol Project, and then make six (everyone uses) Bluescreen Ammo (in Engineering). Other ammo is neat but does not compare as virtually every big enemy is mechanical (walker, orb, specter, codex, andro-2, mechs, etc) and the bonus damage vs mech is too much and it applies to a sniper's pistol.
Spider Suits for the snipers. Grapple (a cable shot Batman device) is free movement to high ground within one or two action point worth of movement away (any height). Can grapple and fire sniper rifle same turn.