Ok here's my suggestion is to replace the Blaziken with Chesnaught that way probably the weakest link in your team is gone, evolve Type Null then put on Flying Memory since it's the only one that can give you some edge. Then just deal with her team up until her Garchomp and just let it Draco Meteor your other team members to death while saving Mamoswine. I'd suggesting giving it Ice Shard for priority and then waiting until Terra has lowered it Special down by 6 then an Ice Shard should KO. For the rest of the team I'd recommend using Swoobat for Nidoking, Leech Seeding the Quagsire, and Palossand so that they are forced to switch out and when they come back in defeat them with super effective damage, Hippowdown and Excadrill should be the least of your worries if you've kept your team healthy and that's how I'd recommend using your team to beat Terra.