Other than the two OVA episodes, the games are:

Psychic Force (PSX, US and JP releases)
Psychic Force: Puzzle Taisen (PSX,JP only release)
Psychic Force 2012 (Dreamcast, US and JP releases)
Psychic Force 2 (PSX, JP only release)

The first game and Puzzle Taisen use cels. I'm 
almost 100% sure that the Dreamcast verion has no 
cels. I'm still trying to figure out if Psychic 
Force 2 has cels to it. . . I'm hoping it does - I
want a cel of Setsuna!!!!!!! ^_^  And of course, 
I want a game cel of Keith!

So Yann, when are you going to post one for sale 
for me?? ^_~~~

Many Sharp Smiles,
--Drac

(And in case anyone is curious, I have all 
releases of all the games except the JP release 
of the first game. ^_^)