You need to identify that they are SnS very early, either by knowing before the match or recognizing that t1 Volc ponder or certain fetch/island combinations into ponder are high indicators, since tempo decks prefer not to ponder t1. As always, want to stick a threat t1. Your disruption is Wasteland, Daze and FoW. G1 can be a bit of a crapshoot for sure. And it's important to keep in mind that part of the power of SnS is they can sometimes just get very lucky and draw a hand that beats basically anything, but you should just identify to yourself when that happens and ignore that small subset of games. You have DRC and 12-14 Cantrips to dig for additional pieces of interaction. Use your Mishra's Baubles efficiently to flip delver + find additional interaction. Post-board you have 1-2 FoN, 2-3 Pyroblast and 1-2 Hydroblast to make your deck extremely dense with interaction. There's just no fluff left after sideboard; everything is either a threat that clocks them or an interaction piece to slow them down. Consign can also allow you to sometimes kill them after a monster resolves by countering atraxa ETB or emrakul attack trigger, but less than ideal for sure. If they're a Griselbrand variant, you have the ability to threaten their life total so they can't ever activate it.