It could use spikes and/or go on all fours in “fast” mode. It’s whatever you design. My main point though is not mechanics, but the significantly lower reaction time. Given enough compute, the world that seems “real time” to us could appear to be slow as molasses to a robot. I think the natural thing to do would be to make it move at the speed that provides a good balance between accomplishing objectives and energy consumption. I think that this speed is much faster than what we’re used to with humans. For eg military robots that balance could be further tweaked in favor of quickly accomplishing objectives.

Compressed-air rockets. Or H2O2 with a platinum catalyst; "decomposition ... into steam and oxygen" https://en.wikipedia.org/wiki/Hydrogen_peroxide#Propellant

We're spit-balling hero-bots, not nasty kill-bots, riiiight?