First: How to acquire Delta Scyther. It is in a house on Route 3, where a hiker will trade it for any steel type. Magnemites may be found in Suntouched Passageway, the short surf-cave after Suntouched, or in Cyan Cavern, the cave before Suntouched.
Now, onto actual comparison. HP Atk Def SpAtk SpDef Spd
Delta Scyther Base Stats: 70 110 80 55 80 105 (Total 500)
Delta Scizor Base Stats: 70 130 100 55 80 65 (Total 500)
The first thing to notice is that Delta Scyther has the same total stats as Delta Scizor. Now, the question becomes - is Delta Scizor’s spread better?
The answer is no. Both Delta Scyther and Delta Scizor have the Ice/Fighting type. This gives:
6x Weaknesses: Fire/Fairy/Fighting/Steel/Psychic/Flying.
3x Resistances: Bug/Ice/Dark.
This is very different from the change from normal Scyther to normal Scizor, where it goes from 5 weaknesses and 4 resistances to 1 weakness and 9 resistances (Ignoring immunities versus resistances and 4x versus 2x weaknesses).
The reason why normal Scizor’s stat distribution works is because its high defensive stats along with its resistances makes it a good tank. However, Delta Scizor gains no such typing benefits. In fact, by losing 40 speed and only gaining 20 atk, it loses the only reason to use this mon in the first place - amazing offensive abilities. Coupled with the fact that the best fighting move it gets is Close Combat, which reduces your own defenses, Delta Scizor has no positives over Delta Scyther.
It can be said that you might want to use Mega Delta Scizor - and the question becomes why? There are many better megas, including your starter’s mega.
However, if you must persist in using Delta Scizor - it evolves via trading with NeverMeltIce, acquired on the 4th floor of the Helios Department Store.
If you want movesets: Bulk Up/Drain Punch/Ice Shard/Knock Off. A bulky moveset that synergizes with Delta Scizor’s increased defensive stats. Roost can be taken instead of Drain Punch; alternatively, Drain Punch can be replaced with Brick Break, Cross Chop, Close Combat, or Superpower, while Roost replaces Knock Off.
Swords Dance/Close Combat/Ice Shard/Knock Off. A fully offensive moveset that requires set up. Stone Edge can also be taken for additional coverage. Icicle Crash can also be taken over Ice Shard for the power. Cross Chop can be taken over Close Combat. If so, Hone Claws is a good swap for Swords Dance, as you might want additional accuracy. .
I would like to end this post by saying: do NOT use Delta Scizor. I repeat, do NOT use Delta Scizor. You will most likely regret it.