Psystrike is a nice buff over Psyshock, but Celebi is the only fully evolved Psychic type that doesn't get Psyshock in the first place, so it's actually only notable as "well, if I was running Psyshock anyway, here's a 25% damage increase".
If you had to rank Psychic with the other types in STABmons, would it be high, mid-level, or low in its utility?
Psychic is in a weird place in STABmons. Raw offense gains are pretty mediocre, particularly for Physical Psychic types, but it has such an enormous list of support moves Psychic Pokemon represent a rare case of genuine unpredictability -most types in STABmons tend to be fairly straightforward in what you're gonna see. Physical Fire types get Flare Blitz/V-Create for overwhelming offense, Special Fire types run Blue Flare, and support Fire types don't exist/already had Will O Wisp anyway. (Castform-Sun is the only Fire type in the entire game that doesn't get Will O Wisp) Whereas Psychic types can be setting Trick Room, Power Tricking to become an unexpected Physical attacker, Calm Mind or Cosmic Power+Stored Power for ungodly offense, Gravity for Ground support (It's too bad Claydoll is the only Psychic/Ground type, and it has Levitate itself, so it's not thrilled), Guard Split/Power Split to steal stats, Heal Block to mess with stall, Heart Swap to steal stat boosts, Imprison to just lock up just about anything (Gothitelle in particular can abuse this), Lunar Dance as a suicide heal out of nowhere, Magic Coat means any Psychic type has the potential to reflect your hazards
surprise, Psycho Shift to clear their own status (While giving it to you), dual screens on literally any Psychic type, Choice Scarf Trick type shenanigans to ruin Chansey forever, and the never-used Wonder Room to reveal that your switched-in Skarmory is about to die to Mega Medicham. There's also potential for obnoxiousness from Meloetta or Jirachi running Luster Purge to just melt your defenses 100% reliability with an OK-strength attack.
So on the whole I tend to rank Psychic as a very low-tier type in STABmons -nobody ever runs Psycho Boost, so unless you're looking at Stored Power in specific Psychic types (Again, especially the Physical ones) get very little help in their straight offenses- and yet it's the one type I'm most wary of any given instance until I've got a handle on what that Pokemon is trying to do. Yeah,
most people don't run...
any... of the myriad Status tools outside of Calm Mind and Cosmic Power, but not only does Psychic have a ton of them, but they're heavily weighted toward completing messing up your plans -with zero warning beyond "hey that's a Psychic type".
Or put another way
straight offense C-
surprise mindscrew S-rank
Do Psychic-type Pokemon gain a lot in STABmons or do they usually already have the tools they need at their disposal?
Most Psychic types already get Calm Mind and Psyshock, so the former at all and the general utility (Bypass Special walls) of the latter are already existent. But in terms of being able to do an enormous array of things, with little ability to predict them ahead of time? Yeah, Psychic types get a
ton out of STABmons.
In the larger context of the metagame, where does Psychic add value to a team and where does it create problems?
I don't understand the latter part of the question.
