well it depends on what you mean by "immobilize"
if you mean by cutting limbs off i don't see why it couldn't cut a suit in half
if you didn't mean that then please explain what you did mean by "immobilize"

but to stay on topic, i've always held the Astray and Murasame pilots in high regards
both because they have great skill and determination not often found in normal grunts
plus that have managed to dish out some serious damage
Minerva anyone? and also they took down Sting, now don't get on my ass at how Sting sucked cause i've heard it all before but he was an "ace" pilot and had a superior suit in terms of firepower and defensive capabilities