Trap Trickster: I rarely use "Hold (button) to (attack)" attacks, and the Traps are incredibly usefull when attacking from a distance, and can attack multiple enemies.
Shadow Combat: He's one of the only SWAP Force Skylanders to have a bottom half with a projectile attack (e.g. Jet, Shake), but there are more bottom halfs that have an attack similar to Prowler (e.g. Jet, Zone, Blade, Bomb). And most of the Prowler-esque attacks are useless unless you're being chased at an incredibly close range.
Even then, most of them don't do enough damage to stop them before they attack you. In addition to this, it takes time to start prowling, so you can't use it when you're being chased. And you can't lure them into chasing you after you've started prowling, because you're invisible. The only three uses of prowling (for me) is going slightly faster, damaging enemies by touching the, and being invisible, none of which improve when you pick Prowler. You can't go through enemies, so the footsteps are useless because they won't follow you (because you're invisible).