I have mathematically proved that the limit is NOT 999 str and def. 
Please observe my beautiful krogs stats. you will notice that by having bulky 3 upon entering a battle it would technically add my 999 with 749 both ways for a total of 1748 str and def. It is essential now to multiply this by 2 since both my str and my def are equal to 1748 and to determine krogs final hp we have to add his new str and def to it. 1748x2=3496 which, when added to 3359, gives us a grand total of 6855 hp
now look of my krog photographed in battle seconds later. And what should his hp be but 6855 the AMOUNT THAT COULD NOT BE ATTAINED BY MERELY 999 STR AND DEF. So, therefore, I believe the maximum attainable str and def is actually 1998 and that is why i think the bulky synergy is arguably the most cracked synergy to ever exist.