I'll share where and how I did this solo, if a second body is not an option for you."Battletoads" difficulty
, Act 1, Stage 4: At The Carn-Evil, area right after hitting the roller coaster switch. Play through to this point yourself in co-op.https://imgur.com/c7UuYsL
I mapped player 2 input (using the xbox accessories in settings) so punch (X) was on B instead. Move both toads to the area where the red arrow is, without triggering the fight. Set up player 2 in the left corner of the 2D background fight area, and face to the right (where Zitz is laying in the image).
I put the controller on the ground so I could hit B with my big toe.
Take control of player 1 and start the fight, and while you tap B on player 2, start racking up your combo in the main 3D fighting area (where Pimple is in the image). Player 2 (your toe) needs to tap fast enough to not take a hit/have the combo timer end, but slow enough so you don't combo and end up moving. The setup is a bit tricky, but I got this on the second attempt solo.
If you mess it up, reload and hit the switch again, and start the setup again.