First off I do not know if you can DI side special, if not then continue reading.
Mewtwo can start a 0 - death grab combo that, from what I assume is inescapable. There's a part of the hitbox of side special that can grab characters in the air, while mewtwo is grounded.
Start's off with up throw at 0% and you can dash away from where they DI. Before they land side b, they will bounce, tilt forwards and do it again. This can be done over and over, I experimented on a level 3 fox which has mixed DI. I side special locked him across one end of Final Destination to the other, being able to finish him with fair/uthrow/dsmash.
Mewtwo can start a 0 - death grab combo that, from what I assume is inescapable. There's a part of the hitbox of side special that can grab characters in the air, while mewtwo is grounded.
Start's off with up throw at 0% and you can dash away from where they DI. Before they land side b, they will bounce, tilt forwards and do it again. This can be done over and over, I experimented on a level 3 fox which has mixed DI. I side special locked him across one end of Final Destination to the other, being able to finish him with fair/uthrow/dsmash.