Its actually upsetting how stupid some of these alien invaders are.
Chitauri-creates flying, slow-moving, whale things that half ass topple over medium sized skyscrapers. Wtf for? Just shoot the goddamn buildings with your lazers dumbass. And flying chariots that leave the pilot who has human level durability horrendously open which basically means the entire aircraft and machine have the same durability despite being made out of highly advanced and much stronger components and metals. Complete fail.
Thanos-releases fast moving deathh machines that can go underground past force fields or annihilate all ground forces when they run over them, does not release them until after he has sent his ground forces to mingle with enemy forces and after they already turned the main part of the field off. Absolutely terrible. Complete waste of rolling death ball machines.
The only thing Chitauri have that can potentially damage Jaegers is the Leviathans and their big ships. The sky runner carts will do nothing.
On the other hand in just the 1st movie you've got Striker Eureka, Cherno Alpha, Crimson Typhoon, Gypsy Danger, and even Coyote Tango, the Jaeger Stacker Pentecost piloted when the first Kaiju came through. Giant man at his biggest height of 175ft is still at least 100 feet shorter than a short Jaeger. And waaaaay lighter. He punched a leviathan out. Jaegers all have huge arsenals that will slaughter chitauri wholesale.