After you collect all of the things T.K. wants you to pick up, go to the nearest blender.

Mix up a Quickstep, Energizer and Painkillers. Next, head to the Arena and go in front of the door that leads to T.K.

Then drink your Quickstep, Energizer and Painkillers.

Now go through the door. When you start the battle, your status affects from your mixed drinks will still be with you.

Next, quickly run across the arena and pick up all the food items.

Then, either use a wrench or haymaker to defeat T.K.