i have a few wishes a character ended up with that i could use some help with, the campaign is a god level campaign where the characters are playing as fractions of a deity. As we are right now, one of them (the on with the wishes) is currently a dragon and is trying to take rule over the rest of dragon kind. I need some help on if to allow these wishes or how to alter them

 I wish my ability to change shape as a dragon allowed me to turn into any type of dragon or monstrosity as easily as I trun into a humanoid or beast.

I wish I could change the type of damage my breath weapon did as easily as I change it for my spell’s damage type.

I wish I had access to all varieties of breath weapons held by both Metalic and Chromatic True Dragons in my true form.

From my perspective, wish is a powerful spell, but if a wish is too powerful, nerf it so the players won't become overpowerful. For example, instead of them becoming a dragon, have it where they turn into a dragonborn or dragon wyrmling instead. This is just a suggestion.

Wishes are tricky business. 

My first thought is that the phrase "as easily as" could be twisted to make your current abilities more difficult instead of making the new abilities that you desire easy.  A lot depends on interpretation.  
Two examples of this taken from my favorite DM are 1)  Ranger: "I wish that [insert name of cleric] could cast the Resurrection spell, just this one time."  The spell was too high level for her at that moment in the game.  Nonetheless, she was able to cast it successfully -- That time and that time only.  The party eventually reached level 20, but that character was never again able to use that particular spell.
The second instance was a fighter who stated, "I wish I had a ring of Regeneration right here in my hand."  He got the ring but it was permanently fused into his palm.  He had to stand with the fingers of his other hand thrust through it for it to function.  

You third wish sounds the safest as it is now worded, although nothing specifies how often you have access to the breath weapons or what strength they are.  Just idle musing.  
I wish you good luck with your wishes.  

I wish I had access to all varieties of breath weapons held by both Metalic and Chromatic True Dragons in my true form.

I agree, the wording is critical. "Having access" doesn't mean owning it, or being able to do it yourself. A dragon breathing its weapon at you could potentially be viewed as giving you "access" to the breath weapon.

In general as a DM, I tend to look for and exploit loopholes in overly general wishes like this ("I want access to all of these things forever"), and don't worry about them so much for specific wishes ("I wish Boromir would be alive again."). True the second wish could go wrong (Boromir never died but instead took the Ring from Frodo and ended up taking it to Sauron), but because the 2nd wish is specific, and selfless, I would be more inclined to let it happen as the player is picturing.

The wishes you listed in the OP are extremely general and far-reaching, and so I would find any loophole I could to make the wish backfire. In essence, you got greedy, so the gods or fates or whatever will punish you.

It seems like you’ve got a bit of homebrewing going on, which complicates things. 

For 1, what is “change shape as a dragon”? Dragons can’t change shape, I don’t think, unless you’ve added that. 

For 2, how is he changing his spell’s damage type? I’m not clear on what that means.

For 3, what is his “true form” at this point? He might have an original form, but is that “true” anymore? And varieties of breath weapon don’t mean exactly the same weapon. You could cut it way back. 

And it might be a little outside the wish, but you could give him the Dragonborn racial breath weapons, or look for a way to do that. 

BioWizard

i'm not worried about being over powered, we're playing godbound characters essentially which is a very high power level system, literally have abilities that can let you lift anything up to the size of a skyscraper regardless of weight and it won't break under it's own weight, normally i'd consider that if it was my normal games but this one is for all intents and purposes a special one

Xalthu
the character is a silver dragon. metallic dragons have the innate ability to shape shift into humanoids, check into the lore, it isn't mentioned in the stat blocks for 5e but it's in the history so i use it
changing it like with spells is because of using the lore master UA for the character
it's not so much a power problem and not exactly looking for a way to nerf any of it but more like what would be quirks and stuff to add on to make it interesting 

There are some things on DMs Guild that open up for divine ranks/epic level play.

I'm combining 2CGaming's epic level rules (they have an update currently on kickstarter), & some things I found around the internet.  I've made a progression for Divine Ranks 1-21 & using a list of divine feats I found online.

The end of the campaign I ran had the PC end up as hero-gods, & the original ones in the setting changed their species upon being given a divine spark, so you could work it that way.  Some of them are Metallic Dragons, so they can shape change.

If they can drop mountains on people, I'm not sure why they'd be bothered about breath weapons, but there you go.

The meaning of each Wish here is very clear. They are limited in what they can do.

There is a tendency for DM's to want to break the wording of very reasonable wishes, such as Eriniel said above. In my view, there is no reason to mess up a Wish this way just because it's a Wish. The thing with the Ring of Regeneration sounds extremely petty to me - using an incredibly rare 9th level Wish spell to gain access to a Very Rare magic item sounds entirely fine and shouldn't be abused. The character could have wished to regenerate back to their full health immediately after taking damage, after all.

Your player has requested 3 reasonable sounding things. What I'd advise is that you implement solid rules for how they play out.

 I wish my ability to change shape as a dragon allowed me to turn into any type of dragon or monstrosity as easily as I turn into a humanoid or beast.

This is self explanatory. The current ability also now allows them to become a dragon or monstrosity. I might prevent them turning into shadow dragons. 

I wish I could change the type of damage my breath weapon did as easily as I change it for my spell’s damage type.

This is phrased in game-term language. "The type of damage" is a rules reference. Ask them to rephrase it to something a dragon would say - "I wish I could breath fire, lightning, acid, poison, radiance, cold and necrotic power in addition to my normal breath weapon." And there you go, easy, they just choose the breath weapon that they want when they use it.

I wish I had access to all varieties of breath weapons held by both Metalic and Chromatic True Dragons in my true form.

This appears to be the same wish as the one above.

I have to agree that these wishes don't sound unreasonable enough to warrant much of a twist. It depends heavily on where the wish came from, to me - if it is their own spell, or a non-sentient item made by a benevolent being, then it should be expected to work as intended, especially with these wishes. If it is being granted by an imprisoned genie, or a malevolent sentient item, then I would expect it to be twisted.

Assuming you decide to twist it:

Wish 1: They can change to the monster easily, but cannot change back.

Wish 2: They can change it, but only between 2 types.

Wish 3: They are a splintered part of a deity, so their "True Form" will not be found until they become whole again.