I was surprised to find out, years ago, that Scizor and Scyther had the same BST. I only saw Scizor in OU competitive battling. Why is that? Can someone help me understand?
Syther is weak to fire electric ice flyng, and has a dual weakness to rock (and with stealth rocks this is unacceptable) only resisting grass fighting and bug. Scizor is only weak to fire with 8 resistances and 1 immunity.
Scizor sacrifices speed for defence and attack, perfect for a steel type.
scizor has more moves in general, gaining access to bullet punch a priority move which works great with technician ability.
that is why everybody uses Scizor.