>>44985354aight aight. Hey mac, let me take a whack at it.
Wonder Launcher, but it's a spellbook with slots you choose to fill while outside of battle rather than having what is effectively the entire in-battle item list available to you. Lets say 3, maybe 4 slots total? or maybe you've got a number of points to spend filling it and things like reviving cost a lot of book space and something like dire hit very little.
also, gimmicks never use a turn, so neither would it. helps set it apart form just using items or the original wonder launcher idea.
You rack up mana, you spend that mana on effects of various costs. Some of those effects can even be things not related to combat itself, if you don't need stat-buffs/debuffs, status-infliction/healing, healing, etc, spend it instead on an increased catch chance, or if SOS makes a comback increased rare help summon.
Heck you could even make player mana consistent between and out of battles and combine it with the O-powers idea.
Fun for in-game cool and flashy without being "too easy" because you have to build up mana one point a turn and then spend it cleverly, its not an instant win button like Z-moves, especially if opponents have the gimmick too, as is common with bosses. And it's fun for competitive, because that all can get tactical as hell.
PLUS it's somewhat within current lore, we already know multiple different practices of magic exists in pokemon world, and that people can learn to use it. It's plausible for it to be mega-user level common in a given country.
The onl problem is, I think this might be TOO good a gimmick, too convenient. we'd miss it when they took it out the next gen, like how people miss the PSS.