what are some recommended team assists for Vergil?

I like a projectile assist with Vergil for sure and any assist that covers the screen/locks down like Sentinel Drones (although I personally don’t use Sent Drones). Unibeam is my preferred assist with Vergil for most situations especially for right/left mix ups and safety purposes. Bolts of Balthak is one that is exceptionally good for Vergil’s playstyle but I can’t play Dr Strange yet. I do know there is solid synergy between the two.

OTG assists work well with Vergil especially Wesker’s Low Gun shot and Deadpool OTG because you can go into Round Trip -> JC -> Spiral Swords extended combos.

Assists that hit at a particular spot (overhead or low) are especially good for Vergil when he is using Spiral Swords. Overheads are better than lows. I prefer Nova’s Centurion Art assist and it doubles as a combo extender as well.

Assists that allow him to extend combos after a Rising Hightime are also good like Jam Session so he can get extra mileage from his ground throw and hard knockdown after Helm Breaker.

Finally, meter building assist like Morrigan’s Dark Harmonizer might be something worth investing in if you already play the character. You can pretty much overwhelm the opponent with the meter advantage and just hammer them with constant Devil Trigger cancels and Spiral Sword combos/mix ups.