Good level-up moves for Durant are Iron Head, X-Scissor, Crunch and Dig. You can breed Rock Slide (Crustle), Feint Attack (Crustle) and Rock Tomb (Sudowoodo/Onix>Crustle>Durant). You can also breed Hone Claws (Skorupi/Drapion) and Thunder Fang (Drapion). There's also Baton Pass to keep the chain going (Scolipede, Surskit, Ninjask, Lediba/Ledian).
Now, you could go all out on offense with Iron Head, X-Scissor, Dig and Rock Slide/Rock Tomb (hits 512 foes super-effectively). You already have 2 Ground moves, but Dig as the fourth move is the only available move that gives Durant perfect neutral coverage (beside Dark, but you've got enough Ghost moves, and Dark instead of Rock gives perfect yet inferior coverage), which is greatly beneficial for sweeping, especially if you Baton Pass an SD from Blaziken (which you don't have to rely on)
See which Rock move you want, Slide is a bit stronger and has a 30% flinch chance, but that flinch chance doesn't matter at all if the foe is faster. Tomb has slightly better accuracy and less power, but the Speed drop can help against faster foes to support your team as well as make foes slow enough to utilize Iron Head's high 30% flinch chance (if you didn't Baton Pass).
You could go for a Dark move instead of a Rock move (still perfect coverage, but 100-ish foes more aren't struck super-effectively). Feint Attack has less power than Crunch, but it never misses, so it can be useful if your next attack has to hit.
There's also Hone Claws, which boosts your accuracy to 93%, which is above 100% with that accuracy boosting item from the O.Dept Store, although I think Durant is better off Attacking right of the bat rather than boosting itself, especially if you BP from Blaziken. Even without the Acc. boost of HC, you still have 88% accuracy with that item. Almost the same accuracy as Blaziken's HJK and how often does that miss? I'd say the first option is better.
You also have inferior coverage since you're only relying on 3 attacking moves, of which Thunder Fang (if you go for it) super-effectively does barely more damage than any of Durant's STABs neutrally.
Or you could run Iron Head, XS, Baton Pass and Dig/Crunch and you wouldn't have to worry about coverage at all since Durant wouldn't have to sweep, you could just pass the buffs from Blaziken over to someone else via Baton Pass if things aren't looking too good for Durant. I'd go for this or the first option.
Rather than farming Heart Scales for Rotom, you could just breed it with a Ditto, pretty sure it would have Confuse Ray and Thunder Wave at level one.
My guess is that it'll be a long long time until we get a Scizor. Escavalier is very good too, but it depends on what you want. Escavalier is bulkier than Durant, not by much on the physical side, by a lot on the special side, but it's weaker (Hustle), has less attack types and it's speed is really, really bad, 20 base. At +4 speed, it's barely enough to outspeed something like Arcanine (95 base) Even buffless Durant has enough speed and power (as well as the moves) to kill oposing Fire types (with some luck) while Escavalier stands no chance. Megahorn is Escavalier's only move with more than 80 BP and even that does barely more than Durant's X-Scissor, let's not mention the other moves.