Kris MK: 322 (Attack) * 218 (Mega Kick) * 1.2 (CS2) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 341,152
Kris Sync: 322 (Attack) * 350 (Sync BP) * 2.2 (CS2 + Haymaker) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 1,004,157

SSG Liq: 448 (Attack) * 133 (Liquidation) * 1.5 (CS2 + PF5) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 361,972
SSG Sync: 448 (Attack) * 267 (Sync BP) * 2.2 (CS2 + Haymaker) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 1,065,778

Kris total: 341152 * 3 + 1004157 = 2,027,613

SSG total: 361972 * 3 + 1065778 = 2,151,694 (6% more damage, a little more than one sync level)

But what if both are maxed?

Kris MK: 362 (Attack) * 218 (Mega Kick) * 1.2 (CS2) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 383,531
Kris Sync: 362 (Attack) * 350 (Sync BP) * 2.2 (CS2 + Haymaker) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 1,128,897

SSG Liq: 496 (Attack) * 133 (Liquidation) * 1.5 (CS2 + PF5) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 400,755
SSG Sync: 496 (Attack) * 267 (Sync BP) * 2.2 (CS2 + Haymaker) * 1.8 (+6 Attack) * 1.5 (Crit) * 1.5 (Sync buff) = 1,179,969

Kris total: 383531 * 3 + 1,128,897 = 2,279,490

SSG total: 400755 * 3 + 1,179,969 = 2,382,234 (4.5% more damage, less than one sync level so whoever leads in sync level also leads in damage)

Grids used:
Kris: https://pokemon-masters-stuff.github.io/?e=0&grid=AAECAwQFBggJCwwNERITFBYYGh8uLw==&o=750&p=Feraligatr&s=5
SSG: https://pokemon-masters-stuff.github.io/?e=0&grid=AAECAwQFBgcJDA8QERIUKCkqLS4v&o=750&p=Sharpedo&s=5