depends what is in the genes... some stayer type TB would probably, some Arabs would too.
I personally wouldn't risk it, but that's just me.... one cheese wire foal was Arab on Arab.... most the time things go fine, but every now and again it doesn't, and if your not willing to take that risk...
if sire of your mare is 16.2 I personally wouldn't do it, had you asked me 2 years ago, before I saved that mare, I would as the others have insisted the foal NEVER gets bigger then the mares uterus allows, but the uterus is not the problem as its very flexible, the problem is the mares pelvic...
I have seen it go HORRIBLY wrong.... you must make sure your pony mare is a genuine pony not a hybrid ei. a pony of size but genetic has big horses up close....
IF your mare is a genuine pony then fine, I have seen a welch sec B about 12.1 get several foals including her first by a TB stallion...
sorry for spelling errors but English is not my first launguage
Anglo colt TU Champion (pure bred) x TB mare
Anglo filly TU Champion x TB mare
Part bred ponyTU Champion x welsh B/New Forest
3 years old, Danish national champion part bred foal, now graded welsh part bred stallion...
as a breeder of Arabs I do of cause believe the Arabian has a lot of good sides to add to other breeds... I have bred a few Anglos by my one stallion and they are super, he also has fantastic part bred progeny.
Danish Warmblood, Trakhener, Hannoveranian all accept pure bred Arabs in their...
many of the gelded ones didn't get gelded till later on though, I know at least two of them that wasn't gelded til 2 and 3 years of age.
regarding siblings as one compares... the gene codes can fall out so many ways, just look at human siblings, im nearly 6ft and about 10 stone my full sister...
well its all theory really as nobody has been able to/ ever will be able to make a qualified experiment.... the same horse cant grow up as a colt and a gelding at the same time ;)
im a firm believer if the horse is not to be a future stallion cut it as soon as possible.
I would advise to buy the foal that ticks your boxes. I've been breeding for years firstly TB, then a few showjumpers, and in 2007 I changed for good to Polish Arabs... breeding is a gamble, you can (like e and others) spend months or even years studying generation back, but a horse has over 200...