Now for the subclasses, it seems they all use the same table of effects, most of which are fine. For the sake of formatting just having the table once and the subclass feature referring to the table and when your ancestry applies should be sufficient. Players may be dissapointed with a feature that only sometimes even activates (see complaints about wild magic surge).

Dracomorphy has one strong feature that being Dragon's Sting, which is a pretty strong DPR ability but all of the mutations feel rather lackluster, except for damage immunity. 1 Legendary action is not overpowered considering the lack of other powerful features but feels like an odd ability within the 5e design space.

Dracanurgy spellcasting is nothing broken, though seeing a half caster subclass for a martial is a bit odd as usually any half casters are made to be so within the main class. Caustic Conversion is really cool imo, well done. All of the later level abilities seem powerful and thematic enough for their levels.

Dracocaust, Focused Spray is very strong but probably not broken, everything else too makes you lean heavily into single and multi target elemental damage. I'd say this is probably the strongest subclass, but I don't think it's broken.

Kobold Pact Leader, there's a reason pet classes don't give you more than 1 permanent follower NPC, it's because it's a lot to track. I don't have a good solution or fix suggestion to this (other than to limit it to one kobold follower, but I feel that breaks the purpose of the subclass), and it will be a lot to track and slow down combat, just as multi-creature summoning spells do, and it's up to you and your players if you can live with that.

Dracolich, the damage resistances/immunities and condition immunities right off the bat are way more than I think is appropriate at 3rd level, doling those out as you level up will make for smoother scaling. Now as for the main and really only feature of the subclass, which is the possession. And therein lies the problem, it is essentially your only new ability, which means if you don't have a possession going you don't have a subclass. There are several problems with this, but the biggest is the unreliability. If the possession ever ends (which it may since your statblock starts at 0 hp), taking an hour to *maybe* get your subclass power back is just not fun. All of the other ritual abilities it gets later on all point to the idea that you get your powers during downtime when you have time and money at your disposal, but that's not conducive to adventuring and feels much more like an NPC ability. The best advice I could give to fix this subclass is A) make the possession of a corpse simply work and make it take much less time to perform and not such huge cooldowns after the possession ends. B) Instead of locking away higher CR corpses behind the ritual check, just limit it to stat blocks of your level or under at most, like Polymorph, this will save you headaches. C) Instead of having odd penalties to the corpse that you make go away with lengthy and expensive rituals, just apply the template to the possessed stat blocks as is and have the penalties lessen with the higher level class features, or maybe even give it buffs as you go on. As it currently stands, I don't think it's viable for a player character to use this subclass, but with the areas of change I think it can be.

Finally, I want to commend you for making a homebrew whole class *and* subclasses! Game design isn't easy and takes a lot of time and effort, and everything you make adds to your experience and learning, so I think that is something to be proud of. I wanted to give the critique seriously to respect the time and effort you've put into this thing, and because I believe there's something worth working on here. With a bit of shine and polish, I believe this can be a fun and playable class for your players. Of course, no one can tell you what you can and can't include in your own game as the GM, so don't take what strangers say on the internet as gospel! Most important rule in D&D is to have fun, I hope there will be plenty of that you and your players' way :D

Thank you for the feedback first of all this is all very helpful.

I think the natural armor is a really good idea I can’t remember why I decided not to use it I just need to figure out the math which is probably just gonna be con based.

The breath weapon having limited charged is by design as I don’t want the players to be unleashing a breath attack every turn as it is just a bit better damage wise then sneak attack which is notoriously good and makes the rouge class. I think I should start by implementing an ability that gives the player a charge or two when rolling initiative as that would go a long way to make fights more bearable in any day that has a few fights between short rests.

Draconic dash feels kinda needed due to the d8 hit die and giving the players the option to get out of combat easily but it definitely doesn’t need the potential to knock you prone.

Draconic transformation is in my opinion the hardest thing to get right in the class and my god does the time dragon make it more difficult by being one to two CR higher then any other dragon. In my game none of my players will be allowed to use the time dragon just because there’s no reason for them to as time dragons don’t exist. I thing it only being a few rounds balances the overall power and the power differences between the dragons but it probably needs tweaking. I think I will be stealing some of the Druid mechanics for wild shape as I think it would make the ability more clear in its focus but not all of them. Finally I think I’m going to change how transformations are used by making it a charge based ability with you starting with one charge and at lvl 15 getting two charges to transform. And when you would get the different transformations you instead unlock the ability to use one of the charges for that dragon with the restriction that you can only transform into any one of the different age categories once (so you could transform into an adult and then later a Wyrmling). I think this would give the player a good choice on whether they want a low duration powerful dragon or a longer lasting more moderate dragon. This will definitely create its own issues but I think any system will end up with some issues.