This core was actually really cool IMO; Gastro & Talon have a lot of defensive synergy. I wanted to avoid just going with a basic, boring M-Sableye hazard stacking stall build, so I went with a basic, boring balance team with Venu instead. I chose curse>toxic on Gastrodon to prevent it from being pressure stalled by Crocune, and it can be a pretty decent win condition at times since it can set up on a decent amount of mons such as bulky starmie. Bulk Up/Wisp Talon is nice to burn Excadrill and thundurus' checks such as Quag/Hippo etc, and is one of the most reliable win conditions against slower teams. Gastro and Talon act as a pretty solid defensive core, with Gastro hard-walling electrics, resisting/walling rock, and absorbing water moves that can threaten talon. Talon sets up on shit that forces Gastro out such as Venu/Ferro; Gastro sets up on Ttar/Tran (W/O power herb) etc. Venu is a really nice mon' on balance and stall, completes a F/W/G core, and acts as a reliable counter to Azu which can power through Gastro with ease if banded. Venu also checks most Manaphy variants, and appreciates Gastro's storm drain since it does not have to switch in on a scald and risk getting burned. I went with a more offensive spread that I stole from one of Cosine's teams, since max defense Venu is kind of redundant imo since it doesn't need max defense to check what it needs to. Venu can be annoyed at times by Ttar's sand, but sand is fairly ephemeral without Smooth Rock and Gastro can take a lot of pressure off of Venu, so it's not really an issue. Gastro should be used as the go-to scald switch-in, since Venu getting burned is pretty annoyng. The fourth slot was originally a CM Lati, then a manaphy, but I finally settled on thundurus: Thundurus gives me a check to bulky talon that can burn ttar, pinsir which shits on everything, and some much needed speed while checking shit like psychic manaphy and roar suicune. NP 3 attacks because a ton of teams are really weak to it right now, and I already have ttar for twave. Lefties>life orb because on NP I find the extra power isn't really necessary most times, and lefties can add up over time since thundurus forces a lot of switches. I considered grass knot, but hp ice is just really nice and I already have talon to lure quag/hippo with wisp and excadrill has a balloon to set up on hippo anyways. Exca removes hazards while shitting on offense which is nice; also a nice fairy check and obligatory steel type. Balloon lets it set up on common checks such as lando and hippo (although I don't see Hippo too often anymore, but I've seen it on the rise a little bit). Ttar provides rocks, as well as sand support for exca. The set is standard support Tar, but I went with Twave instead of ice beam/fblast since ferro/lando aren't really issues (other than RP), and twave is nice to not have to rely on SE hitting and to just spam in general because I'm shit at this game and things are a lot easier to kill when they're para'd. Tar pursuits lati, gengar, zam, torn, and other shit like talon, and is just a great support mon' in general. Tar is also the only reliable Zard-X counter on the team, but exca under sand and gastro can check it decently, and rocks + sand prevent it from being too much of a nuisance. Manaphy with psychic can be annoying as fuck to deal with since, but every other set is dealt with pretty handily by gastro/venu and thundurus checks every set. I've noticed chansey can be a little irritating with toxic, but it's fairly easy to pressure and pivot around and full stall isn't too common right now. Fuck medicham too.
tl;dr it's a bunch of shit with setup moves + venu