Eh, I think you worry too much about stabs and using the "main" stats.
A rotom event before post game like platinum will be cool. Actually, being able to change forms will be even better because unlike the old games, the appliances now have actual unique types meaning using them will be entirely new experiences. Perhaps a little overpowered so not right after the second gym but just having them available before elite four will be nice.
Also, i've made a list of sinnoh mons who cannot exert their full potential before e4 / post game. Most of these aren't new and i'm not saying these mons are bad, just that they might not be what you're expecting so people can keep it in mind.
Luxray: Assuming wild charge is post game, it has no really stab or even coverage as crunch has been moved to lvl 56. You'd likely be stuck with thunderbolt, iron tail, normal filler, utility move
weavile: no stab moves other than ice shard...For some reason, night slash is at lvl 60. I don't even think it's feasible to breed icicle crash if you want to pull such shenanigans since the only mon i can see with icicle crash on the list is cloyster who isn't in both dp and pt variants of the dex.
mamoswine: icicle crash is an egg move. Still, 80 special attack so maybe ice beam can work?
wormadam, mothim: no good bug move until lvl 50
Leafeon: leaf blade is at lvl 50. You do have razor leaf though and leaf blade isn't that late compared to the other gens.
Chatot: No boomburst so still same old weak chatot.
Dusknoir: old news; no poltergeist so practically no stab.
Expecially during main plot (aka, before the big juicy rematches and/or champion match), stats are low enough and enemies arent optimized so you're free to work off the weaker stat or using unstabbed coverage without much issue.