The issue of how bots recognize one another
The two things that made me think about this was those constructed cold and IDW Megatron being called a narcissist for never having his face modified no matter how much his body is modified(which implies that the normal procedure involves that a bot has their face modified as well to a certain degree).
And what just adds to it is the scene in the heavily G1 inspired "Bumblebee-Win if you dare" comic when Bee says that he gets a 'feeling' that certain vehicles are Decepticons but he doesn't know how to tell for sure(he adds that someone smarter, like Wheeljack, might know). It leaves more questions than answers.
Another odd situation is when Hot Shot(in UT's Energon comic) says that he knows the bot who appeared before him (Galvatron) is Megatron despite believing Megatron to be dead and merely watching him from a distance, but he doesn't know how to explain the correlation he made. And in Beast Machines, Rattrap instantly recognized Silverbolt in his new techno-organic bot mode without any indication that it was him(and without any delay).
Regardless, let's get things started.
1. Facial recognition
In IDW's Last Stand of the Wreckers, Pyro was asked why he "stole" Optimus' look in a joking manner which marked that somehow even similarly looking bots can be told apart(although Optimus can't be told apart from his SG version nor from his other counterpart, Nemesis Prime; although, somehow, his "lookalike" RiD Sourge can be identified).
And there's another issue one must take into account: bots who are born without a mouth can alter themselves in order to get one. I think it's simply safe to assume that bots don't take facial recognition to the level we do.
Otherwise there'll be other issues: How would a bot recognize another who was industrially mass produced and thus shares the body type and mug with hundreds, maybe thousands others.. or bots who had their face modified? Because sometimes they just do. There was even a joke Swerve pulled that Bluestreak would classify as someone who would remind Rodimus of Prowl. And their (constructed cold bots) paint job can hardly be taken into account because any bot at some point can decide to change the paint for something that represents them better(or pull a Senator Shockwave😅).
Maybe there's a more simple explanation at least when it comes to that so called face alteration. Maybe the alteration is much smaller than implied, thus it hardly matters. But when it comes to serious body alterations, like whatever Bumblebee underwent to become Goldbug... idk.
2. Overall body recognition
a. Alt mode
In some series bots can be recognized or attempts to identify can be made just by their alt mode(take the situation of the Prowl trying to identify Ultra Magnus by his Cybertronian vehicle mode in RiD 2001) while in others they can even recognize them despite having taken Earth vehicle forms; and then in some verses....changed paintjob = probably different car
In some series they can tell a vehicle is a bot and not a human vehicle while in others they actively try to engage in conversations with parked cars
Same about other altmodes in Cyberverse
b. Database
In Transformers Prime the Decepticon database has entire schematics of them (more than likely in order to enlist weaknesses and strengths)
In TF Victory the Autobot ship identified Deathsaurus in a similar manner
Alas this is something their ships could do so it's irrelevant to us per se and other than Rewind, bots were typically shown to face issues when trying to use large databases or to learn things quickly(Nautica, Tailgate, Bulkhead).
3. Other forms of recognition
In some verses they can recognize one another even by voice, while in others it takes speech pattern. In Cyberverse, Perceptor recognized the sound of Deadend's engine.
Kaon doesn't have eyes and is said to use echolocation.
Lastly in Bayverse they can smell a bot's presence(although whether they can ID the bot or not remains to be seen). In G1 however, Ultra Magnus could find Rodimus by tracking his "gas fumes"(in Return of Optimus Prime Part 1).
Conclusion?
There's clearly a lot to be taken into account when it comes to how they can possibly recognize another bot without using any device to help them, including that it may vary from verse to verse. Is it an unique energy/heat signature? If so they should be able to detect it while scanning for Energon with greater ease maybe, although we know that at least in Beast Wars it is indeed possible. Also they shouldn't be able to remain unrecognized by merely wearing cloaks. Is it a movement pattern? Would be harder to tell for cars. Spark detection/recognition of some sort? It would leave unexplained why they can't tell whether an opponent perished.
The only certain things are that they can typically tell a bot from a human vehicle by speed, or from a regular jet by movement which is constant across series.
Most promising means to ID so far: scent.
Notes:
-I am not taking into account faction energy signature; this is all about IDing bots in general without the help of an AI or external devices-especially since those signatures are often dampened.
-In IDW Mtmte#1, Cyclonus could both sense and ID a bot via Spark signature. Sensing Sparks does occur at times in IDW but the capacity to ID was never attributed to anyone else. Moreover Spark signatures can be dampened. Cyclonus' situation was likely an isolated plot device. They can also sense the signatures in Earthspark(it doesn't help them ID a bot though)
-In Beast Wars it was shown several times via Waspinator that bots seem to have some sort of heat signature that they can detect/see.
There's no telling however whether:
-it applies to other verses;
-it's a beastformer only thing;
-It's Beast Wars specific(aka whether the Cybertronians evolved in due time to get there).
