I wrote about my thoughts in the "Is Pac-Man our first summoning character" thread.
"Each type of fruit will probably have different properties, similar to the different Pikmin Olimar plucks from the ground. The Cherry and Strawberry will probably be pretty weak, as will the Orange, as we saw it bounce off of Mega Man's shot in the trailer. After that, I'm theorizing the fruit will get stronger and stronger. The Apple will probably do moderate damage, the Pineapple will probably roll across the ground, the Galaga Alien homes in on someone and attacks them, the Bell will probably do some sort of sound wave attack, and the Key will probably be something very heavy and damaging."
After watching the trailer again, it's definitely for sure that the item gets put into Pac-Man's hand after you let go of B because we see him throw a Galaga Alien at Fox in the air, and there's no way he charged it that fast from a jump.
Also, I was wrong on the Galaga Alien. After watching the trailer, it doesn't home in on a character. It simply goes forward, does a loop, then continues on its path.
I'm super interested to see what the bell and key are going to do.