@djedditt released a rumble hack for Wario Land 4 a few days ago. Tried it on my EZ Flash Omega DE and it's excellent, feels like what the game should have been all along.
Download here:
https://www.romhacking.net/hacks/8027/
Here is the description by djedditt from romhacking:
Exciting news for Wario Land 4 enthusiasts! A groundshaking update has burst onto the scene to make your Wario adventures more vibrant—literally. Read on to discover how we’re shaking things up!
Rumble Functionality
Download here:
https://www.romhacking.net/hacks/8027/
Here is the description by djedditt from romhacking:
Exciting news for Wario Land 4 enthusiasts! A groundshaking update has burst onto the scene to make your Wario adventures more vibrant—literally. Read on to discover how we’re shaking things up!
Rumble Functionality
- Just like the unique rumble feature originally found in “Drill Dozer” and “WarioWare: Twisted!”, this patch adds comprehensive rumble support, providing tactile feedback for many in-game actions and events. Experience every smash, dash, and transformative twist as Wario battles quirky bosses and uncovers hidden riches on his Game Boy Advance expedition.
- Not limited to the handheld experience, this patch also adds rumble compatibility with the Game Boy Player for GameCube, allowing you to enjoy the game on the big screen with controller rumble. That’s right, this is the first patch ever to add Game Boy Player rumble support to an officially released game!
- This patch works on most hardware and/or emulation software, including:
- GameCube with Game Boy Player
- EZ-FLASH Omega Definitive Edition flashcart
- insideGadgets 32MB 256Kbit FRAM rumble flashcart
- MiSTer hardware emulators
- mGBA emulator