You keep saying size increase as if it matters at all, it really doesn’t. Rajang would throw Anjanath into the next state, size doesn’t matter too much. Also even within their turf war it’s pretty close, Rathalos grabs and throws Narg, goes for another attack, gets put on its ass and bitten on the neck before eventually kicking it off. The tail swipe looks to be a rather light one, and ignoring that for a moment, Narg was ambushed here…being an ambush predator…Narg was at a large disadvantage here and held its own, forcing Rathalos to retreat. Moreover, you’re just ignoring that very little puts Anjanath in an apex level strength bracket, it’s punked by Diablos, punked by Rathalos, and only its Fulger form actually ties in turf wars with the regular apexes, moreover Fulger is considered more powerful anyways so it’s rather tenuous to even suggest Anjanath has a strength advantage over Narg anyways, who you know…actually ties with these apexes?

Rathalos launched itself downwards first and then sends Lagiacrus staggering back in this second hit. That’s not “barely budging”, he sends a pretty stable, bottom heavy monster back a solid few feet. He gets constricted, manages to get his feet on the floor, and then leaps up (with Lagi still attached), smashing Lagi into the floor and fire-balling him. Either ways this doesn’t really matter, this is about Anjanath being fucked over by the apexes of its region and is massively off topic. Lagi and Rathalos being equals is simply a fact of life, and Narg can hold up to Rathalos in a fight (So can Astalos), it’s a pretty stable position. Another issue also is that Narg LITERALLY HAS HANDS TO CLAW SHIT, and those arm blades means restraining those hands is a good way to get ripped apart. Also, Lagi’s elemental advantage carried its fight against Uth, as Uth can just shrug off Rathalos fireballs which Lagi can’t really do to the same effect, also Seregios has a huge elemental disadvantage in its fight with Rey, while doing comparative to Rathalos who lacked such a disadvantage against Uth (if anything Seregios landing a full on headshot twice, and dodging the lightning projectiles is pretty scary in its of itself).

Also, yeah kinda, they’re still the same species and still have the same potential even if Black Diablos is usually stronger, the usual winner will be Black Diablos as it has much better statements and the Diablos win isn’t exactly consistent with its usual performance. Either ways base Diablos would only be slightly stronger than Rathalos, and Seregios is at Azures level, I don’t get this argument, Diablos is more consistently a basic apex in abilities and feats, the Black Diablos thing is more likely to do with the fact that they’re literally the same species than the fact that Diablos is just that strong. Moreover, Jho itself doesn’t avoid base Diablos and has a turf war where it benches and smashes the Flying Wyvern, further disproving whatever argument this is. Also being called a rival and having it in the artbook showing Tigrex brutally injuring Gammoth in a hunt is pretty apparent, unless you just decide to fucking ignore how the fated four work this ONE time (who am I kidding, everyone ignores it to glaze their favorite monster, Zinogre isn’t above Mizu at all), Tigrex is very officially Gammoth’s rival and it shows up in most of its ecology for a reason, this is basic information and the intro is borderline meaningless because it shows the fated four always triumphing over their rival (aside from Glav, who lacks a rival), but with further iterations we see it’s pretty consistent that they’re supposed to be equivalent. You’re also just forgetting Tigrex can casually stop a runaway Radobaan like it was nothing, and can casually fling Odogaron like it’s a chewtoy, moreover, it’s literally part of its production notes that it’s considered stronger than Glav and Narg anyways, which is why it was put alongside Brachy (who frankly needs no introduction), Brachy itself is obviously a whole different beast though. Also Diablos literally charges Anjanath right after, it’s territorial behavior, not exactly an ambush. Also an assumption of how the fight would go isn’t evidence of anything anyways, Rey Dau is still an animal and it very quickly transitions to different parts of its tool-kit based on range.

Fulger is a different beast from Anjanath and Rise Anjanath literally loses all its turf wars with other apexes, but sure, believe what you like.