I keep buying Elixir's. Particularly, the red ones that doesn't say that I can't use in battle. But, when I click "I" or the satchel, none of them are in there. I need help. :( I can't move on in this battle without using them.

Elixirs and draughts can be used from the Manage Party window. To get there, you just click the arrow icon to the direct right of the satchel icon. Then click the button at the bottom left that says, "Use Item". Click on whatever elixir or draught you'd like to use, and then click on the party pet on which you want to use it.

Hopefully I answered quickly enough to be useful; good luck on your battles!

Thank you! It worked. :)