I kind of love the idea of different elements, but i dont think they'd really work in the way you presented them, as thats not really how this game works (or atleast from what i watched and read so far).
Since all it takes is 1 fatal hit to kill you in this game, injuries dont really exist, sure breaking a leg can make your character limp, but its quite manageable and the usage of the jetpack upgrades pretty much negates its setbacks with enough skills.
So heres what i was thinking might make more sense :
since health gauges dont exist, elements shouldnt be focused on killing you directly as it quite beats the purpose, and we already got us fire swords and arrows to cover that,
Lets think about the basic elements you spoke of, first of all, i dont think acid is pretty much chemical fire if implemented in such way, so i was thinking more of slime as a replacement.
Element inflicting enemies : enemies that exist to inflict certain manageable debuff's, like for example the spidtron (or however he's called >w<! ) imagine how broken he'd become if he would be shooting bombs that knock you down, while simultaneously shooting laser beams, it'd mean each time you get knocked down theres a high probability that it'd cost you your clone, or entire run for that matter.
Slime inflicting enemies : focused on ranged battles [Slime's status effect : slightly slows down the player's walking speed by 5% , stackable to the total of 20% slower walking speed, while also slowing down the player's energy regeneration rate by the same amount, the debuff stays for 5 seconds , recharging each time the player is exposed to it, reaching 10 seconds if the player reaches the maximum stack of slime debuff]
Enemies that i had in mind : a flamethrower-like robot that sprays slime in a short range over small bursts in a cone like range.
archers with slime induced arrows that do not kill on impact but rather inflict the slime debuff.
enemies with slime jetpacks that are quite similar to the garbage drones, that fly in a straight line while also spraying down slime puddles that lingers for a short time, the enemy stops spraying slime after 3 seconds , so that even if it was at the end of the map it wouldnt create a giant puddle where it'd force the player to step into , and always targets the shortest path to a direct line to the players direction, enemy only encountered in open areas.
Electric inflicting enemies : focused on ranged battles [ Shock's status effect : temporal Paralysis in a medium blast radius so that not every shock means the end of your run, since close enough bots are also paralyzed, although you could still die if you were still paralized while an enemy was just far enough to not get hit by the blast radius but also not too far away to miss the punish ]
enemies that i had in mind : mage-like drones that charges medium time to shoot relatively slow moving orbs that explode on impact inflicting the shock status effect in a radius, and long time to mark an area around the current position of the player to summon an electric orb that explodes in a short time.
elements would sound cancerous , as we already have knock downs instead of paralysis, and might be completely over looked but it also gives the player access to more weapons and abilities like exploding slime inflicting bombs or lightening staves that shoots a continuous shocking lazer beam that is controlled by the player which consumes 2 bars to charge, that could be useful in taking down gaint hammer bots with minmum risk if you have the space.