I would just like to point out that an Elite's shield goes down after one physical strike from an opponent.
Because they can put several tons of force behind their Melee blows. Thrown Weapons don't work like that, and neither do projectile weapons.
Presumably if a Yautja were to actually get up to an Elite and were to Melee a Defenseless Elite with a full powered punch then the shields would drop.
But the thing is, you are taking Game Mechanics a little to far. Meleeing in the game was Simplified like a lobotomizing someone of an already low IQ... They take absolutely Nothing into account when fighting hand to hand in the game, and treat the attack like a Zero Range projectile. The World doesn't work like that though. If they wanted to make it more realistic, then Melee would probably use a quick time event that pits players against each other in a timed game of rock paper scissors. That would be fun, and more realistic than it is... but even that isn't too close to reality either.
The plasma caster literally destroyed a tower vaporizing it with a single blast. Thats more than enough to take out an Elite.
Ok, a High Powered Shot could presumably do that. But what's the time it takes to charge that shot? I would imagine that it would take a relative amount of time to charge it as the damage it would output. Larger shots should need longer charge times.
Also armor made of Dlex is highly resistant, very similar to the spartan armor.
And even Spartan Armour fails after a couple hits. Energy Shielding is the way to go, it protects you from headshots, and things that would otherwise kill you dead.
Again I will state in this setting the preds have the upper hand, it would be different in a large scale war. This set up has the advantage of guerilla style fighting which in every instance I have seen or read goes in favor of the preds.
Except they are fighting against an opponent that has dealt with Cloaks...
Is not hindered by the terrain...
And has Motion Radar virtually destroying the Predators advantage of stealth.
The Preds would have to do a Massive Rethink on their hunting strategy, as Sangheili aren't like humans. They're stronger, and much much more combat orientated in their thinking.
As well, rather than Fear of the enemy as you would have with Humans, they would probably evoke an Intense Hatred of the enemy. Cowards that only use Cloak and hide in the shadows, never fighting like Real Warriors.
Also the pred in the novel i mentioned defeated 150 soldeirs with massive firepower against one single pred. Even if it was the Thai army thats impressive seeing as how he beat them in just a few hours. I couldnt see a low ranking Elite doing the same.
No, you wouldn't because a Low Ranking Elite doesn't have the kind of equipment that Preds just give out to their children...
Sangheili have to Earn their equipment, they have to show that they don't need that equipment to become proficient killers. And Besides, if even a low ranking Sangheili warrior was equipped with Cloak, he could do the same thing against the Thai Army.
Because against an enemy that has no tech that can see through your cloak, they're easy prey for anything.