I'm not sure that's exactly how LBs work, lorewise.
Looking at Chimatsuri for example, all it says is that it's using the aether suffusing a battlefield - which probably means a ninja could even do it solo, provided they are able to use the ability in the first place. A similar restriction is put on Final Heaven (though the phrasing: "Cannot be used until the practitioner is prepared to reach beyond mortal limits into the divine" is borderline 4th wall breaking).
In the case of Pulse of Life, it says it draws upon the reserves of all allies present, but it doesn't state any restrictions as to how and when it can be used - so if there are sufficient allies around, yeah, a WHM WoL would be able to use it, with a higher strain put on the allies the less there are to draw from (probably even killing some if there are too few or their aetherial reserves are lacking).
