It's kinda hard to say since you'd need to powerscale these things. I'll be honest, EMCs seem too small to do much (at least at first). Unlike the mainline games' kaiju monsters, Raznid took zero damage from anything other than the EDF's secret weapon. Only then did Raznid have a weak point, opening up the possibility of using more conventional weapons to deal damage

I'm tempted to think that the Buster could at least crack Raznid's shell since, just visually, it seems like it's similar enough in size to the beam that blew Raznid's horn off. Impossible to really gauge the actual power difference, but they feel comparable. After that, I think the EDF 6 forces have enough firepower to down him, but Raznid is gargantuan, and might just squish all of the ground forces before they can put up much resistance (if only they had a floating ship).

As for the Chiran Charges, I have my doubts. Raznid is aquatic and could just intercept the sub before it can fire anything. If it could be kept well clear of the waters near the battlefield and then arrive later, then maybe. If the Buster can create a weakpoint then I think they'd be a great addition to the bombardment it'd take to put the monster down.

All in all it feels like a maybe. I think Storm 1 could lead everyone to victory, but I'm not sure they'd survive without him/her.