Scyther's Dark move and Nidoking's Bug moves will do 1.25x damage, because Alakazam is not just weak to Bug (i.e., to Bug moves), but also to Dark (Dark moves). Scyther's Steel Wing will do 1x damage.
Pokemon get a "same type attack bonus" (commonly referred to as STAB) for using an attack of their own type. If Scyther used Fury Cutter, the move would do 1 * 1.25 * 1.25 damage. Otherwise, beyond using usually one or two attacks to take advantage of STAB, pokemon in the main games (less in Go) usually have a focus on having attacks that provide them additional "coverage" by giving super effective hits against a wider range of pokemon.
