This is if they both invest fully in bulk, of course. Foongus can hit a Defense and Special Defense stat of 309 each at level 100, but it's HP stat is significantly lower than that of Amoonguss. I'm curious if Foongus could stand up to it's father.
Amoongus is slightly bulkier.
Amoongus defensive calcs:
252+ SpA Abomasnow Blizzard vs. 252 HP / 252 SpD Amoonguss: 284-336 (65.7 - 77.7%) -- guaranteed 2HKO
0- Atk Abomasnow Ice Shard vs. 252 HP / 252+ Def Amoonguss: 56-68 (12.9 - 15.7%) -- possible 7HKO
Foongus defensive calcs:
252+ SpA Abomasnow Blizzard vs. 252 HP / 252 SpD Eviolite Foongus: 236-278 (69 - 81.2%) -- guaranteed 2HKO
0- Atk Abomasnow Ice Shard vs. 252 HP / 252+ Def Eviolite Foongus: 50-60 (14.6 - 17.5%) -- possible 6HKO
Hope this helped!
