A Final Fantasy game with once-a-day amiibo summons or something would be so cool. Basically like free spells in a way, that don't cost any of your MP or anything.
Here's some ideas with the Smash Bros Mario cast (I might do more later but I wanna play more Hyrule Warriors Legends).
Mario Finale: A Fire spell stronger than any other, and catches all enemies. Effective at clearing enemies in an area where lots of enemies are weak to fire, doing unparalleled damage. On enemies with strong fire resistance, it's not very effective. On enemies with neither resistance or weakness to fire, it does moderate damage to all enemies.
Poltergust 5000: Sucks up all enemies and shoots them back out, putting them in a Dazed state for two turns.
Shower of Peaches: Performs an elegant dance while peaches rain from the sky. Soothes the party, removing all debuffs. Also heals the entire parties HP by 20% of their current max health.
Bowser Bomb: Performs Bowser Bomb, functioning like a stronger Quake spell. Ignores all status weaknesses and always deals a great amount of damage, but it cannot hit flying enemies.
Will of the Cosmos: Plays a small animation depicting something similar to how Rosalina restarts the cosmic cycle in Super Mario Galaxy's ending. Restores all HP and MP (and whatever other energy resources), and removes all buffs and debuffs, and revives all fallen party members. However, it does this for both the player's party, AND the enemy party. The purpose of this summon is to reset the battle to a completely neutral state, in the event you accidentally ran into a battle while being under-prepared, or if you make a wrong move and want to start over. Perfect for key boss fights or foes you need to fight once to assess their strengths and weaknesses. It doesn't wipe any Scan/Libra data you acquired while fighting the enemies, so you can keep the knowledge you acquired during your initial struggle. You may also keep any items you stole from the enemies using Thief abilities.
Airship Fleet: Bowser Jr, in the Jr Clown Car, leads an airship assault on your enemies. Very powerful and will ground any flying enemies (or get rid of them if there is no ground below them), but has a 50% chance of missing entirely.
Mega Yarn Yoshi: Comes through your enemies rolling along a giant Yarn Ball. Does moderate damage to most enemies, but has a chance of having all enemies get caught in the Yarn Ball, completely carrying them away from battle (except on bosses).
Shake It!: Wario scrambles in and picks up the enemies one by one (regardless of size), and shakes them like crazy. Lots of Gil will pour out of them and into your wallet, and there is also a chance of getting rare items and materials too.
Mega-Vitamin Prescription: Gives the entire party a dose of his mega-healthy, mega-brand prescription. Removes all debuffs, and applies every single buff in the game to every party member for three turns. However, it has a small risk of nasty side effects, which could put certain members at critical health (3% of their max HP) alongside everything else.
