You have to run Hidden Power. This is better flavor wise imo.
It may be better flavor wise, but honestly I think this makes the metagame far worse. Purely physical Pokemon in no way benefit from this change without running a useless move, stall will be hard pressed to find space for such a move, hidden power is STILL a very, very weak STAB in general, and the vast majority of Pokemon running hidden power use either fire or ice, giving them a SR weakness. In all honesty at this rate the metagame will probably be standard + 1 hidden power Pokemon, which makes it pretty stale.
I mean, of the examples I've seen in this thread, none of them seem like improvements over their standard selves. HP Ice Thundurus takes a whopping 50% from Stealth Rock. The HP fighting version can't touch Dragons despite the SR neutrality, which I think makes it even worse. Things like Aggron and Heatran with HP flying and venusaur with HP rock will have a move they never use at all which I don't think is worth the extra typing, which is something that also applies to Ghost/Poison/Dark Gengar, Dragon/Psychic/Steel Lati@s, and Electric/Steel Flying Magnezone (I guess that one could hit grass types, but it would still rather have HP Ice).
On the claim that it'll make stall too strong, consider that both Fairy and Normal are deprived as typings which means you can't exactly pick and choose Pokemon with those typings to your heart's content.
I think if this metagame wants to succeed either the extra typing will have to be based off IVs (Which benefits physical Pokemon too), or Hidden Power will need a power buff (say to base 90 power) to be even remotely worth using. I like this metagame and it has potential, but at this rate I doubt it would deviate much from standard if at all.
