Best Of

A few thoughts:
• I’d consider Vox over BRB. They take Shocker easily (not that Shocker really needs a direct answer tbf), can nuke through Spidey99 with degen, and will be much safer for Spidey Supreme than Juggs thanks to Vigilance. They don’t work as well against Nimrod because of the Debuff Immunity but I think he’s doable with Onslaught anyways if it comes down to it.
• Kate can handle SC if you’re particularly deft. The pseudo-taunt she has helps with baiting specials until SC exits Lock-on and as long as you maintain the Coldsnaps she’ll still be doing good damage that whole time. Certainly unideal over a harder counter with power control but she can do it. Definitely would do it better than BRB at least since SC goes Shock immune whenever he gains his Armor up Buff (you can temporarily disable it with Pulverize but it will always come back before you can start really stacking shocks).
• I’d definitely take Wiccan over Juggs. He does the same job of handling phase 4 GM with RC immunity, but also is a very good option for Knull. You don’t need Juggs’s extra stats for GM, and Mantis will be perfectly fine without his easy-bake intercepts.

All in all I’d personally consider going in with Onslaught, Vox, Kate, Chavez, Wiccan. A few of the fights are gonna sink a few revives but the right side of Necro tends to do that, there’s a few too many problem fights for you to get perfect counters for everything.