
+1
Side B Jump Cancels, if you do them at ANY point, even just for recovery (makes surviving Lylat Cruise and Pyrosphere Omegas so much easier), will make you over 50% better than other Jr players that never do it. Keeping track of available jumps (including the Side B Jump Cancel) may be tricky, but you're generally coming back to the stage unless someone reads your return angle with a spike or catches you during your Up B with a weak hit like

's NAir or

's Jab (not even pressing the airdodge button will save you if THOSE moves hit).
Punishing his Side B is surprisingly hard during lag, due to its speed and safety (he can JC out of it at practically any point if he sees a counterattack coming). Punishing with his Side B, conversely, is surprisingly easy, and the payoff's pretty big (at 85-105%, it combos into Up B --> A (Hammer) for the KO!). Depending on how much you use Side B JCs, he might be a mid-to-high level execution character.
He shines in FG Teams, due to his versatility in roles that can rival the Mario Brothers. Paired with someone with low KO power but high damage building power? Jr will lead the team in KOs with Side B JCs. Paired with a strong KO-er? Jr will support with Mechas and Cannonballs.
He's great at protecting his allies. Side B (JCs) lets him reach opponents pretty quickly, and Mechas & Cannonballs cover his partners very well.
His excellent recovery lets him go deep off-stage for the edgeguards, even without walls. Thus, he can help relatively grounded allies (ex.

,

,

) secure KOs when their Smashes fail to seal the deal.

+1
Traversing though his advancing or retreating (possibly even stationary, depending on positioning and MU) wall of projectiles as a character that struggles with handling projectiles as it is (ex.

,

,

, etc.), is a total pain. *Recalls vivid footage of ChrisG's Morrigan/Doom/Vergil team in UMVC3 walling out folks for entire rounds, complete with Astral Visions, "SOUL FIST! x??" and "Hidden Missiles!" XD;*
Especially when he gets an ally like

,

, or

in FG Teams to help fortify it.
Sure, KO-ing is even harder than it already is, but eventually, your projectiles will either KO by themselves, or set you up for a KO move like UAir, sweetspot NAir, or BAir. He's a low execution character, unless you're moving either with or away from the Can while air attacking pretty often, which may make him a mid-execution character.
Much like Jr, he really shines in FG Teams, due to the likely potential of being paired with someone with strong KO-ing power (ex.

,

,

, etc.) that benefits greatly from DH's cover fire (not so much Cans, but Gunmen and Clays, definitely).
However, when paired with someone with low KO power (

,

, another

, etc.), he WILL have to get in to score those KOs, and a DH that doesn't recognize the need for himself to do so is a team that's going to lose.
He is also fantastic at protecting his allies from getting KO'd, particularly when projectiles and approach moves are involved. His Gunmen, Clays, and Cans are excellent for warding off projectiles like those from

,

,

(except Thoron, but he can

, crawl and DTilt under that.

), etc. Even approach moves like the Side B moves of

,

(especially his!),

,

, and others can be blocked with his projectiles.
If given a walled Omega stage like Wii Fit Studio or Nintendogs, he can go surprisingly deep for the edgeguards, even when the opponent successfully dodges the Can, because he can wall-jump. :o

+1
Her range may be terrible, but if she does land anything, it's going to hurt. Especially if she lands both hits of her NAir (14%!). Aside from Down B timing, mashing Up B, and shorthop Side B, she's a relatively low-execution character with good overall movement speed.
In FG Teams, she's capable of both Guilty Gear!Jam-styled rushdown (featuring Deep Breathing that can help score KOs, and she's even got Neutral B and Side B to cover her team's approaches) and a surprisingly effective camping style with Headers and uncharged Sun Salutations at the edges if given a partner that can occupy the other team. Several of her moves hit on both sides of her, allowing her to fight upclose on 2 fronts and even handle getting surrounded better than others.
Much like DH, if given a walled Omega stage like Wii Fit Studio or Nintendogs, he/she can go surprisingly deep for the edgeguards, due to wall-jumping abilities.
All 3 benefit tremendously from friendly fire being off, and all 3 are absolute beasts to face during Sudden Death, should you venture out to FFA or Teams, where SD is a surprisingly frequent occurrence. Jr's Mechakoopa KOs, whether thrown or walked up to you. A raw Side B KOs, and he can STILL JC afterwards for virtually any aerial that also KOs. All of his ground moves KO, even his 4-frame DTilt, which WILL catch spotdodges.

Thus, he can and will chase you all over the stage.
DH can slowly but surely encapsulate you to the edges with all of his projectiles that can KO at that point, even Gunmen (if its Sombrero or Brown Coat). Even if you break through all that, you've got DH's disjointed aerials (not including NAir, but its sourspot does KO) and Tilts to contend with.
Virtually every single one of WFT's moves, aside from Down B, NAir's 1st hit, Jab's 1st two hits, and uncharged Neutral B, KOs! Including the Soccer Ball and Up B.