By Pokemon like Tyrantrum and Rhyperior, I meant all Pokemon similarly neutered by a burn but are still GSIs to Fletchinder. So like Blastoise, Barbaracle, Slowking, Magneton, etc.
Braviary:
Bronzong and Diancie both lose to SubBU Braviary. Diancie doesn't do enough with Diamond Storm to beat it and Bronzong can't do anything to it except Psywave I guess? Which still doesn't break Braviarys Substitute consistently. I guess that means Braviary has no GSIs? ._.
Samurott:
Samurott 2HKOes Jellicent and Poliwrath with Grass Knot. It has a chance to OHKO Venusaur with Ice Beam after rocks. Lanturn avoids the OHKO from +2 Samurotts Megahorn, but it does ~58% max with Volt Switch so idk, I would list it as a SSI.
Sharpedo:
Might list Gurdurr as a GSI for Sharpedo. It can come in and take any attack Sharpedo can throw at it, then ko with Mach Punch after a round of Life Orb recoil. You also have Amoonguss listed twice as a SSI.
Houndoom:
Flygon is a GSI. The slow defensive variant can take a +2 Dark Pulse and OHKOs with Earthquake. The fast defensive variant can take a Dark Pulse + Sucker Punch and ko with Earthquake. Scarf Emboar takes a Hidden Power Water and OHKOS with Superpower.
Mega Steelix:
Hariyama and Hitmontop are not GSIs. They rely on Close Combat to damage it so Earthquake definitely beats them.
Venusaur:
Amoonguss loses to all varients of Venusaur unless you decide not to run Synthesis on it for whatever reason.
Tyrantrum:
Choice Banded Earthquake 2HKOes Rhyperior and Mega Steelix so they are not GSIs. I don't think Crunch is good enough or even used enough to remove Bronzong from GSI but then again, you have Togetic as a SSI for Flygon because of Life Orb Iron Tail lmao, as if that's even good or used.
Rotom-C:
Specs Thunderbolt 3HKOes Trevenant and Trevenant 2HKOes with Shadow Claw. Not a GSI.