I was thinking about the fusion blades, but the problem is same as with the Gauntlet - The Knight is i believe I4 (at least 3), which means the commander might not even survive till he gets to attack him.
You would have to give him some serious meat shield, which would be problematic as no meat shield we have or could have is fast enough as to let the commander deepstrike and then let them join in.
Yes you might try your luck and outflank 20 Kroot, then join them, but still....
The second problem with that strategy is - you cant blow him up in a single attack.... you simply cant..... well ok you CAN but the odds are extremely against you, so its more like "you most likely wont blow him up in single attack" (onager gauntlet). Being a superheavy, at a pen Roll you inflict additional D6 wounds.... thats not enough unless you soften him up before with some shooting, as the Commander has only 3 attacks, and WS4. Hitting on 4+ ain that hot.
It might be possible if you have a full unit of shield drones, and join them with an Onager Gauntlet, and Fusion Blade commander ((or Farsight and Fusion blade.... Or all three if you really want to go expensive).
The shield drones are really fast, have T4 which doesnt really matter as you will be facing a 2+ to wound shooting anyway, but have a 4+ invul, and come in good numbers.
Unless he charges, the Knight has 3 attacks. Lets say he hits with all of them, wounds with all of them. 3 drones dead. Ok. Not even counting the saves. Matthamer wise it would look completely different of course.
Then your Fusion blade, and Farsight go. They should be able to strip at least 4 wounds (though i d say they should be able to bring him down, both weapons being melta or armorbane you are bound to get at least one or two pens that can spill to D3 or D6 if lucky) before the stomp attack falls.
Thats just a theory tough. If anyone has the option and time to test it, be free to do so and please do share how it performed