Nope, Nagato doesn't have resistance to sealing, he hasn't shown to break free from a seal, doesn't matter how many sealing jutsus he has.
And yes, the OP needs to equalize speed for a fair match. If not this is a stomp and should be close.
Nevermind, with speed equalized your point is moot, Meliodas can still take a hit, so no way his Soul Hax wouldn't work, Nagato won't be able to evade every punch Meliodas throws constantly.
And what stops Meliodas sealing him, again?...,right, nothing...., Nagato is featless in that matter...
Just becouse you have a lot of weapons, it doesn't make you inmune to them.
So Meli has a wincon