The difference between having an actual chainer and not is massive. Tidus is hard as hell to pull off perfect 47 string chains with but even partial chains are doing serious damage.
I can't kill the robot in one turn but I can do it in two. I'm using Tilith, WOL, Ace, Tidus and DKCecil. I take Tidus or Orlandu as friends and neither is better or worse than the other. Tidus chains with himself and Ace can chain decently with Orlandu. First turn takes him to about 60% and second turn finishes him off.
I should finish Brotherhood up over the next couple of days and that will be a big upgrade for Tidus. 65% right now with 10% from the raid coming and another 5% from relics.