If for example OOT is not able to be played at all but a dude hacks the code and puts it on an emulator, then is that wrong or not?

Legally it’s wrong, but there’s an argument to be made that since Nintendo doesn’t offer this game, technically their are not losing profit.

The dude didn't hacked the Code of OOT and the dudes behind the Emulator also didn't hacked or pirated the software of the device. Its called clean room development and is totally legal; it would only become legally questional or outright illegal when they reuse codes they attained from the reverse engineering of the devices software.

Dumping the ROM of a Cartridge is also not illegal as you own the Cartridge and therefore the Software/ROM. Providing it to others who may or may not have the Cartridge, now THAT is a grayzone.

So the argument still stands across the board= Emulation is not Illegal, regardless of Nintendo spouting that false claim or using Emulation for their own retro games collections or VC or Nintendo Online.