

Doctor Doom is probably Taskmaster's single best friend, and you will generally never be wrong putting him behind Tony Masters in either 2nd or Anchor position. Doctor Doom is a capable damage engine via TAC or DHC, and Taskmaster can use all three of Doctor Doom's assists extremely well. Plasma Beam is useful for full-screen coverage and late-combo extensions, as well as giving Taskmaster the ability to convert off his air back throw. Those same extensions can come off Molecular Shield, which also enables Task to convert off his front grounded and air throws, and give him a slow, meaty assist to cover an approach. Finally, Hidden Missiles can help him fight airborne characters like Magneto or M.O.D.O.K. who desire to hang out in the corner and zone you. Additionally, Missiles enables Taskmaster to do unique combo extensions that pump his already impressive damage into the stratosphere. All three assists enable unblockables with good timing, though in terms of ease it goes Missiles > Shield > Beam. However, none compare to the ease of use of Taskmaster's other best friend, Dante.
Dante is the 2nd best support character in the game, and this is just as true for Taskmaster. Jam Session is the unblockable-enabling assist. If building your strategy around unblockables, pick Dante. A simple Jam Session call to lock the opponent down and keep them from pushblocking away enables Taskmaster to easily land a (blocked) L Sword Master (623L) and follow up with an H headbutt. From there, he can follow up with either Lights Out (236H) if in the corner and with appropriate assists, or with X-factor to secure the kill. This is all in addition Jam's fantastic defensive utility, which can and will bail you out when the opponent is rushing in while it secures you hits when you have them backed into the corner. S+ tier assist, and Taskmaster makes great use of it. Devil Trigger is a safe DHC, and Million Dollars is an excellent bit of cleanup to kill anyone who isn't finished off by your looped supers. Finally, Dante's TAC infinite allows for Timer-Scam strategies, which can be very powerful on a team with a bulky point who can either bully or zone as required.
Vergil is the best or 2nd-best Damage Engine in the game and his utility for Taskmaster in particular is surprisingly strong. Taskmaster can protect Rapid Slash even full screen by using his arrows (236X) or Legion Arrow (236XX), and Rapid Slash enables certain extremely damaging combo extensions which can then lead flawlessly into Spiral Sword loops, netting one-touch kills on the entire cast without the need for a TAC. Vergil is very meter-hungry and Taskmaster can be an able battery for him with his 1.1 million hp and ample chip damage. Spiral Swords and Devil Trigger are both safe DHCs off either Legion Arrow or Aegis Counter, and Vergil can even use Taskmaster's arrows to do teleport shenanigans. Amazing pair.
Spencer is a uniquely utilitarian pick for Taskmaster. His ability as a damage engine and strong mid rivals that of Vergil, though his anchor capabilities pale a bit before the Son of Sparda. Spencer's Slant Shot assist restands the opponent, allowing for certain unique extensions that Taskmaster cannot get off any other assist in the game, such as following up after Lights Out after an unblockable, or following up after his Front Throws. Spencer's ability to loop Bionic Maneuvers hypers combined with Taskmaster's complete lack of Wallbounces means that he can secure a kill against the whole cast off a single hit. What's more, Spencer actually quite likes having Taskmaster 2nd, being able to utilize Taskmaster's lateral arrows assist in his incoming mixups and to get an additional up-grapple off a team hyper combo juggle into a full combo. Taskmaster and Spencer have uniquely strong two-way synergy and the pair is absolutely worth your time.
Dormammu is an excellent 2nd behind Taskmaster on point, the pair covering for one another's weaknesses splendidly. Taskmaster serves as a superior point character with his ability to hang with the faster rushdown who would maul Dormammu at 99. He also serves as a battery, chipping the opponent down or even securing kills while accruing meter which Dormammu can then use to cash out for either Chaotic Flame or Stalking Flare, two of the highest-return hypers in the entire game. Chaotic Flame as a DHC after Legion Arrow secures many kills which other hypers would fail to manage, and Stalking Flare is an unconventional - but effective - way to set up Taskmaster's unblockable - though it is surprisingly difficult on incoming. Furthermore, Dormammu quite likes either taskmaster's up arrows or (more commonly) lateral arrows assists. Finally, Taskmaster is one of the best characters in the game at using Dark Hole, being able to use it both for late-combo extensions and also for easy unblockable setups in neutral or on incoming.
Everything Doctor Doom does for Taskmaster, Iron Man can also do - if he has to work a bit harder to get there. Iron Man serves as a damage engine off DHC or TAC, as well as his Unibeam assist doing many of the same things that Plasma Beam does, and being slightly better for random unblockables.
Sentinel Drones is another excellent choice for Taskmaster, giving him a slow meaty assist to dash in after and a good - if not great - vehicle to deliver unblockables. Ronan Healy has proven the effectiveness of Taskmaster with drones. Taskmaster can protect Sentinel fairly well between Shield Skills and his various Arrow specials and hypers, and Sentinel provides decent DHC synergy to Taskmaster as well, with Plasma Storm in particular being a good cleanup hyper if Sentinel is on 2nd.

Taskmaster works quite well with his fellow mercenary Rocket. Either Spitfire or Pendulum are excellent choices to back up Tony Masters, and Spitfire in particular enables several fun and unique juggles, such as a linked triple Charging Star; while Pendulum is also a fantastic assist full stop which Taskmaster can use to either convert into a full combo or extend at high hitstun. The DHC synergy is nothing short of excellent, with Rock and Roll being an excellent damaging DHC that can do many of the same things that Chaotic Flame or Million Dollars do. Mad Hopper is an excellent and safe DHC on a blocked Hyper or to if you desire to get Taskmaster out, and Rocket can use Taskmaster's assist better than many characters thanks to his unique mobility and teleport mixups.

The Sorcerer Supreme is another great choice for Taskmaster, with Bolts of Balthakk being a good vehicle for instant overhead M off Web Swing in addition to its stellar lateral coverage and its power as a high-hitstun extension. Alternatively, Eye of Agamatto assist forfeits this neutral presence for a near-inescapable incoming unblockable setup. Spell of Vishanti provides Taskmaster with an excellent DHC or Team Hyper Combo to clean up kills which he might fall short on, and Strange is a strong anchor in all the ways that Taskmaster is not, capable of cleaning up in the same was as a Dormammu or Vergil.
Taskmaster and the dog work quite well together, and he is one of the best characters at abusing cold star for easy unblockable setups, especially on incoming against characters with no air mobility. When paired with another reliable partner like Doctor Doom, Amaterasu can be amazing backline support and has a good safe DHC in Slow and a good damaging one in Okami Shuffle. Taskmaster doesn't help Amaterasu as much in return, but most of the time you want to be playing with the dog behind Tony Masters.
Littlest but certainly not least, Dagger Toss assist is incredibly powerful with Taskmaster, especially when empowered with King's Armor. Placing Arthur 2nd at round start enables Taskmaster to act as a battery, build up to 2 meters, and then safely DHC into King's Armor before immediately dry tagging back in, now with perhaps the best lateral coverage assist in the game. Dagger Toss enables Taskmaster to convert off full-screen arrows (236L) by plinking up 3-4 times and linking with Charging Star into a full combo. Combined with his 9 points of projectile durability from a fully charged arrows, Arthur's dagger toss either doubles it (unpowered) to 18 points or nearly triples it (empowered) to 24. All in all, the pair works quite well together, and what King doesn't have a few mercenaries under his command?
Hawkeye is another excellent choice behind Taskmaster, as Greyhound is a premier assist for Tony Masters. Greyhound gives Taskmaster throw and unblockable pickups without needing to spend meter or x-factor. Taskmaster/Vergil/Hawkeye and Taskmaster/Dante/Hawkeye are both standouts in this regard, and both teams are extremely powerful behind Tony Masters.
Magneto serves many of the same purposes as Hawkeye behind Taskmaster. Disruptor is an incredible assist in neutral and in combos, and enables throw pickups and unblockable pickups in addition to its other uses. Magneto is best placed in third position, and the best mid for this pairing is probably Dante or Dormammu.