So I finally figured out music. I put a tune in the "game." And I finally found out ground detection. I used that to make the elephant jump. Now I can make some ledges and begin the game. I will wait a little bit though. I bought an Everdrive so I can test the game on a real Genesis. If it works. I'll continue.
You press A to jump. Like I said before, I'm imagining a Bubble-Bobble-type game where the elephant jumps around and stomps on the grapefruit enemies.
I did not however put in gravity. It made the jumping look awkward since he'd land at different y positions. So instead he moves up pixel by pixel and down pixel by pixel.