should we be able to have a sub race of dragon turtle to have as pets and allies

I don't understand the question. Subrace refers to playable races in 5e.

If you are asking if you can have a homebrew monster based on a Dragon turtle but (presumably) smaller and weaker as a pet, then that is 100% up to the DM, and not anybody else on these forums.

I mean like a dragon turtle that is weaker then normal and can be played as like its is a race that is playable by subrace I meant like a subrace of dragon turtle that you can play as

also it is clear that nobody wants to have a dragon turtle as an friend so this is gone forever

Quote from bortle1456 >>

I mean like a dragon turtle that is weaker then normal and can be played as like its is a race that is playable by subrace I meant like a subrace of dragon turtle that you can play as

 So "should there be a variant of Dragon turtle as a playable race?"

Up to DM. But since Dragon turtles are really freaking strong, I would discourage it.

Quote from DxJxC >>

Quote from bortle1456 >>

I mean like a dragon turtle that is weaker then normal and can be played as like its is a race that is playable by subrace I meant like a subrace of dragon turtle that you can play as

 So "should there be a variant of Dragon turtle as a playable race?"

Up to DM. But since Dragon turtles are really freaking strong, I would discourage it.

 i mean like play as one that is a weaker then a normal one cause i know they are strong thats why i said they should be weaker so you can play as one like as a dragon born like you are like a tortle that is like a dragon turtle that is humanoid like they can go on all four and all two and they can breath steam normal like a dragon turtle but it dose not do as much damge but they can hide in shells to and no short or long rest per breath attack cause that is just annoying cause your fighting and you breath fire and then you have to take a nap to do it again like that would suck when you reliaze they need warmth and you might start a fire so you can stay warm but then during an attack you cant burn the enemy that sucks thats why for the dragon turtle race you can breath it every 3 rounds but yeah just get a tortle and give dragon turtle powers and make the powers weaker thats it

My eyes are bleeding. Punctuation is your friend.

So you want to play a Dragonborn descended from a Dragon Turtle? Okay, that's basically just a stock Dragonborn with the Brass/Gold Draconic Ancestry.

You want to play a Dragonborn with the abilities of both a Dragonborn and Tortle? Without the limitations? Nope, I'd never allow that. Others might, but don't hold your breath.

So you want a Tortle with a dragonborn's breath weapon. Up to DM, but I wouldn't alow it since it is a strict improvement over an existing race.

i meant like its just a tortle that is a decendence of a dragon turtle. also i nkow about writeing i just suck at it but i like storys also its a dragon tortle with limits also the powers of the dragon part are weaker  but the limts are that the breath weapon only works as long as your belly  has some water in it so just drink water and your good for the breath weapon and it is weaker. another limit is that you can breath water and air both but you can not talk under water or bite as that will boil stuff around you. also you do suffer some effects of being part dragon turtle one you can not reason with other dragons just normal dragon turtles and you can not speak coomon it sucks but you can speak dragon turtle and normal dragon the reason is because normal dragon tortles live near dragons or they just dont live near normal pepole (also is it a bad thing when punctuation is my freind i never got the meaning of that saying).

I had actually considered writing up a Dragonborn descended from the Dragon Turtle as a subrace concept.

In practice, though, it still followed most of the rules of the Dragonborn... your breath weapon would be a steam breath that deals fire damage, but can't ignite flammable objects.

Instead of having elemental resistance, you'd have a lesser version of the Dragon Hide Feat from XGtE, so you would have an AC of 13+ DEX when not wearing armor

You would also be able to hold your breath for 1 hour.

Ultimately I didn't really bother with it because I realized it just ended up being a janky Tortle with a breath attack.

If you want one as a pet, I would say that you might be able to get your DM to have your character find a Turtle Dragon egg and raise the baby. A baby Turtle Dragon would probably be about the size of a large dog, and they live so long that you could probably have it with you for an entire adventure and it wouldn't grow too large to be unwieldy. Maybe to the size of a horse or something.

Or you could play a character with race of Tortle and class of Sorcercer and pick up the Dragon Breath spell.  Get Warcaster feat to maintain concentration and you have yourself something very similar to a Dragon Turtle.  

one thing is the fact that the dragon turtle is amphibes and so that should make the charecter amphibes cause i mean its a dragon turtle they breath water and air so yeah just that but good idea.

Quote from bortle1456 >>

one thing is the fact that the dragon turtle is amphibes and so that should make the charecter amphibes cause i mean its a dragon turtle they breath water and air so yeah just that but good idea.

   True.  But keep in mind that all aquatic mammals and reptiles in real life cannot breathe water.  They surface every once in a while to breathe air.  This is actually more efficient for them from a physics standpoint.  Anyway, being able to only breathe air is not a very limiting condition in the vast majority of campaigns.  Also, Tortles are capable of holding their breaths for a very long time, which reflects the real life reptiles it is sort of based on.  

true i guess there could be two diffrent types of them cause there are diffrent types of tortles so it would affect the dragon part so i guess it goes both ways