Alright, so as I've been told, Fomortiis starts with summoning. Sure, it may seems he can outnumber Two, but there's nothing stopping Two from just removing them with BFR by just waving their hand or pushing them back with their telekinesis, something that they do in a many of the episodes they have appeared in.
If Two manages to BFR Fomortiis, there's no way the latter can get back since the place he is sent to is a pocket dimension outside of the main universe, which seems to be a common perk in Algebralien's BFR as seen with One and Four, so unless he has feats of traveling through different dimensions, BFR should be a solid wincon to get rid of him.