How can we make unbalanced fights more fun for the underpopulated faction?

Coordinate, it does miracles as I recently discovered!
My squad pushed back a zerg literally 3 times our size.

Small caveat: I haven't even played the game yet; I'm downloading it.

Ideas like "+25% more health" or damage bonus etc are pretty terrible IMO for a more or less twitch based shooter.
However: should there be a resurrection limit?
Suppose you rush out a spawn point, and put a shotgun blast point-blank into 1 enemy face, and get gunned down.
Now, you can respawn at the spawn point, (so no real loss)
but the "zerg" takes no losses either: medics can just revive in a few secs.

What happens when a medic can only revive 6 players, with MAX suits counting double?
certings could increase this. Even so, that would be a pretty big shift from current gameplay because reviving is the current task of medics; even moreso than healing. Without constant revivings, zergs can bleed to death.

A different option is a timer: say, normally, a medic can revive once every 15 sec. With certs this becomes every 10 secs.
But, if you outnumber the enemy by more than 50%, this number goes up;
a 50% numerical advantage increases the lockout timer for reviving a friendly by 25%,
a 100% numerical advantage increases the lockout timer for reviving a friendly by 50%. (so, at max cert level, you could revive a friendly every 15 sec. )
This would make medics desired, and mean that reviving a killed medic becomes extremely important when you outnumber the enemy, to keep reviving/healing up.

Obviously numbers can be tweaked; but a 50% numerical advantage shouldn't result in a 50% longer lockout, as that removes the factions numerical advantage in a meat grinder scenario, and despite the numbers, it is possible the under-populated faction actually has more vehicles..

Id be happy for a large XP bonus for the underpop faction. Its already in there to a certain degree at the moment, but maybe bump it up a little bit more. When 1 kill starts granting you 3-4 certs. It will be a bit like Seagulls to a Chip. They will be coming from everywhere.

So for example if you look on the map for a spawn and you see a 1-12 Allies and 48+ enemies, there could be a something which says 300% underpop bonus reinforcements needed, and the bonus would last until you either take the base back or it caps to the enemy.

Pre-Buff/nerf Zephyr Libs were fun for dealing with underpop.

Make respawn time and revive longer for the bigger force.

There was a similar idea in PS1 where consecutive deaths increased the spawn timer. It was not very popular, and only aided defenders in the context of underground and defensible bases.

Besides, the medic spam that accompanies all zergs would render such a feature absolutely ineffective.

For starters: Tie the spawn countdown timer to the zone population percentage.

Hmmm, yeah. If only some genius would have posted the idea of putting medic-rezzing on a timer.. oh wait!

Other base options: alternating shields.
Atm, to my understanding, shields in the game are on _all_ the time, until base is captured or a section is captured shutting of shields.
Make a base with walls, with a few entrances, which have shields.
During "capping" time, these shields will go offline, sometimes one-at-a-time, sometimes all at once, etc.
By capping/destroying shield generator, the attacking faction can extend the shields-offline duration.
But, eventually, the shields will pop up again.
This would create a more "attack-waves" thing; because when those shields pop back up, the defending faction needs to flush out the attackers inside (kill medics & sunderers inside the base; then everything else; although disabling spawning into the base while the shields are up would be nice). A similar thing could be done indoors, or for sections of a base etc.An attackers wave would have to be able to hold position, defending the ground inside the base already conquered.

When outnumbered, "base defense" consumables become cheaper: cheaper grenades, cheaper mines,.. (but you would only be able to purchase a limited amount at a time; no massive stockpiling during that one fight you get outnumbered 4-1)