Actually, you can use all-stylus, all-buttons, or a mix of both.
It's beautiful; I beat the game and rarely used the touch screen at all, except when I felt like it.
[spoiler=FINAL BOSS SPOILERS!! and stuff]
It was pretty awesome. Wanted to summon Crystallux (3V, 4Me) and Eclipse (3J, 4Me) but only had 3 Me on standby. Summoned Crystallux (putting set Djinn to 0V 1Me 3J) and before Eclipse could be summoned, Rief used a Djinn, raising the Me set to 2, and then Sveta used Eclipse, killing the Chaos Chimera.
I didn't expect the timing to go that well. I was honestly worried that Sveta would move before Rief and screw everything up. But she didn't.
Also, my main party is Matthew, Eoleo, Karis, and Amiti.
this lineup. Currently ready to fight Dullahan for the final Summon Tablet, Iris.[/spoiler]