Polymorphing a Familiar

[Randomthom]

I'm currently playing a wizard (conjuror) in a campaign that has reached high levels (I'm lvl 15 atm).

I have a Pseudodragon familiar and want to use Polymorph Any Object to turn it into a Medium (Young) Brass Dragon.

This is obviously replicating the Form of the Dragon I spell.

By my workings, the duration is permanent (+5 for same kingdom, +2 for same class, +2 for related, +2 for same or lower intelligence for 11 total.)

What I can't work out is the exact effects of the spell. Obviously my familiar gains the Str, Con & Natural Armor, movements and resistances etc. of the Dragon. Does it also gain additional strength & con (and lose dex) by gaining two size categories?

What if I later decide to cast Form of the Dragon III on it (as a temporary buff spell)?

The base stats are listed below.

Thanks!

Felix, Male Familiar Pseudodragon Dragon2* CR 1 ;
Size: T
Face: 2.5 ft. Type Animal/Magical Beast ;
HD (2d12)+2; hp 53;
Init +2 (+2 Dex, +0 Misc);
Spd Walk 15 ft., Fly 60 ft.;
AC 24 (touch 14, flatfooted 22),
*Bite +11 0 ft./BPS (1d3-2 20/x2 Primary T ) or *Sting +11 0 ft./P (1d2-2 20/x2 Primary T );
AL: NG;
Sv: Fort +6, Ref +7, Will +10;
STR*7, DEX*15, CON*13, INT*13, WIS*12, CHA*10

[CasualViking]

You, in this case your familiar, gains +4 Str/+2 Con. He also gains +4 Str/-2 Dex for being Tiny before polymorphing. He also gains a +4 natural armor bonus, 5 natural attacks, flight, darkvision, burrow, energy resistance and vulnerability. He loses his own "abilities based on form". He also gains a breath weapon usable once per casting of the spell, but it's 6d8 fire so nobody cares.

In the end, your dragon ends up with 15 str, 5 natural attacks at +9 for 1d4+2 damage each. Not worth it.