Should I prioritize Pokémon on their base strengths or try and shore up a weaker stat? [duplicate]

Considering how small the difference is here, any effect will be barely noticeable...

...which is not going to stop me doing the maths.

The damage formula was discussed in this answer. It looks complicated but the bit we need is that incoming damage is proportional to 1/defense.

The hp formula I found here was a lot simpler than expected. The important part is that it's proportional to stamina.

Defense and stamina do basically the same thing- they increase the amount of incoming damage you can take without fainting. As mentioned above, damage taken is proportional to 1/defense. This means that virtual hp is proportional to defense*stamina.

IVs are added to base stats to get the total stats. Yes, they matter this little.

So, for the above:

• 15 def, 14 stam gives us 262*175. 45850 vhp
• 14 def, 15 stam gives us 261*176. 45936 vhp

The Metagross with higher stamina is 0.19% tougher. An unbelievably tiny amount.

In general, this shows that when dealing with defense vs stamina, higher IVs in your lower stat have a more noticeable effect.

The same is true of attack, but choosing attack over defense or stamina may be more situational.