Physical/Special split was in gen 4 when it went from types determining if the moves is physical or special attacks
Normal, Fighting, Ground, Rock, Steel, Bug, Poison, Ghost, Flying, and Fairy (Fairy is Normal type in the field) are Physical Attacks
Fire, Water, Grass, Electric, Ice, Dark, Psychic and Dragon are Special Attacks
you can probably circumvent the null type aggron and bronzong got from their seeds with moves like Soak, Trick o Treat or Forest's Curse or forcefully eject them with something like Red Card to restore their types, Aggron has a base stat of 60 in sp atk and sp def (which on the field become the same stat) so while null typed, any of the special moves will do reasonable damage
To explain how Sp Atk/Sp Def works in Glitch Field here is an example: if a Pokemon has 140 Sp Atk and 220 Sp Def, it's Sp Atk AND Sp Def is considered 220 this makes pokemon who are great special walls,, good for special attack damage too
Contact/Non Contact moves and other stuff like Bomb type moves, Sound moves etc still exist so abilites and items related to them will still work and moves that affect them too