I thought the V Joe Bomb trick was known for quite a while. It debuted alongside a Spencer combo in Vanilla. Being hit by the Bomb or blocking it resets the combo and the assist call.
why do you like the Iron Man/Akuma shell so much?
IMO top 3 assists of Vanilla MVC3 were Haggar, Tron and Akuma in that order. To fight against them you only had the option of playing a full screen game utilizing beams. Iron Man's beam assist is the best beam in the game IMO.
In Ultimate despite being nerfed, Akuma Tatsu is still top 3 assist and Iron Man's Unibeam has even more utility as the universal assist HSD nerf didn't affect Unibeam all that much as it still locks opponents in place. Not only that but Iron Man's Repulsor Blast is also much more useful in the meta game present in UMVC3 and more characters can take advantage of it.
The thing was that I never used IM and Akuma on the same team in Vanilla because there was no need. IM could handle anchor position before, now he needs a minimum of one assist to play his game to his optimum level. While Sentinel Drones are arguably the best assist for IM due to various tricks like the Repulsor Trap, I personally don't like playing Sentinel despite the great synergy between the two.
Akuma Tatsu gives IM a lot of things. It makes his pressure/block string way deadlier as he can convert the pressure into a scary high/low mix up situation. IM can hit convert off of even the nerfed Tatsu but the conversion varies from Unibeam to jump loop combo to Repulsor Blast to Proton Cannon. In the corner I have a few options selects against the opponent where I do j.f+H into air dash d/f plus Tatsu assist call. This OS the air throw and if they block or tech it they will have to deal with a Tatsu lock down set up. Advance guard is negated by the air dash in thanks to IM's new dash cancellable normals. In addition, Tatsu extends IM's combos for ample damage and also allows him various reset opportunities. Finally, Tatsu also aids in IM's defensive game as it wards off attackers in conjunction with IM's normals/specials, creates some space and just in general makes it harder for people to attack IM. That small breathing room that Tatsu gives can give IM enough time to settle into a comfortable neutral or even an advantageous position. The new changes of IM's dashes go well with Tatsu assist along with the cr.H change.
In the reverse order, Akuma of course benefits greatly from Unibeam for both his teleport mix up and his high/low. You can also use the Beam for various reset situations. Akuma is also one of the characters who can convert off of a Repulsor assist thanks to his new Air demon flip ground bounce move. Plus they both have Beams they DHC into each other and Akuma's down angled beam DHCs nicely into Proton Cannon. While IM himself doesn't have a safe DHC, he can in turn spend another bar into Akuma's multi fireball for actual safety.
Now going back to my 2 teams that use this "shell". Vergil gets great mix ups/wake up game off of Tatsu along with fuzzy guards and other lock down set ups. Tatsu is amazing with any form of teleport and Vergil's normals make it a cinch to confirm off of Tatsu. Vergil of course benefits greatly from a beam so that he always has a full screen presence with Unibeam by his side plus I have a little Spiral Sword set up with the Unibeam and Tatsu. Vergil is also one of the characters who can convert off of Repulsor and I am especially enjoying experimenting with Repulsor + Vergil. Don't have to worry about DHC synergy on this team either.
That isn't even the scary team though... more like a team that happens to work well made of my 3 favorite characters. Firebrand + Repulsor is a true death loop unblockable set up although strict in timing. Firebrand is also one of the characters who can easily convert off of Repulsor thanks to Bon Voyage. That assist provides great coverage to Firebrand in general. The Tatsu assist is for possible right/lefts with Demon missile, instant overhead high/low mix up with j.L (the main reason why I want Tatsu as well) and even potential fuzzy guards. Firebrand can easily DHC into Proton Cannon although he loses a lot of damage going into Akuma's DHC (not a big problem either). This team is still under a lot of scrutiny but I think this team is real good for Firebrand. I think Firebrand is godly in UMVC3.
I don't think IM + Akuma is some godly shell that people should be using but I feel comfortable with it because I started learning the game with Unibeam or Tatsu as a main component of my team plus I feel comfortable using the characters. It's a major plus that I like those characters and enjoy playing them.