Engine Swapping

Is it possible to drop the 2.5L engine from the 90-92 Toyota Supra into a 94 2.5L MX-6 although the drivetrains are different??

anything is possible with enough money. Sounds like a lot of headaches to me though.

Newer cars like the ones you're talking about had very tight engine bays. You might be able to make it fit if you are willing to give up several things like power steering, maybe redesign the entire front suspension, and do a lot of cutting and welding, but I've never tried it so I can't say for sure.

it won't work since that 2.5L is an inline 6 it will be too long to sit sideways in your mazda's engine bay and you'll be very hardpressed to find a FWD transmission that will bolt to it. You could convert the car to RWD but that would involve cutting the firewall and floorboards and putting the gas tank in your trunk.