Since several people claimed that is set is bad I would like to outline some cards that i would consider to be viable in a competitive format:
Beedrill:
With the number of usefull speical energy cards Persistent Sting is actually quite good. You can potentially use Mustard to bypass the evolution process by using Marnie, Bruno and Mustard as the draw supporter engine and by using Oranguru and Galarian Articuno V in addition to PokeGear 3.0. However, it is under the opponent's control when and where they attach the special energies and some main attackers such as both Urshifu VMAX even discard the special energies to utilize their main attack. I would consider Beedrill a card of interest but I am not certain that it is competitive viable.
Blaziken VMAX line:
Blaziken V is a decent Basic that can even be used with Blaziken VMAX when it has Memory Capsule attached but the main attraction here is Blaziken VMAX who can accelerate to two benched Rapid Strike Pokémon which helps a lot to stream attackers.
Inteleon line:
Sobble is a nice Basic Pokémon that can bench Basic Rapid Strike cards fast which thins the deck and potentially increases the speed of the deck too. However the real gem here is Inteleon. Quick Shooter is perfect for Rapid Strike decks that aim to hit the bench since it handles Mew and increases the damage than can be done.
Rapid Strike Urshifu:
Since this card merely needs one Rapid strike attachment I could see it in a Rapid Strike Box which attempts to hit for several weakness. Being a Water type is a bonus here. The only problem is that Kubfu is not a Rapid Strike card.
Dracozolt VMAX line:
Rumble Break is a decent turn one attack on the Basic Pokémon V since it slows the opponent down and Trap Spark combined with Giant Bomb is a decent low cost attack which even allows Dracozolt VMAX to use Cheryl. The second attack is also decent since it hits for a solid 200 damage and can utilize Triple Acceleration Energy. The weakness to Fighting hurts.
Galarian Articuno V:
Psychic Construct is a nice ability which can be used in several decks that benefit from cards in the discard pile. It helps a lot to make Rapid Strike Mustard more playable and could be used to summon Inteleon or Luxray from the discard bypassing the usual evolution rules. I can also see it in Mad Party decks and potentially Castform decks to discard stadium cards or Mad Party Pokémon, respectively.
Hatterene:
Witch Sonata is a build-in Escape Rope and Psychic could actually do a decent amount with several decks that tend to need three energies to attack. However, being a stage two Pokémon that cannot be cheated out with the Mustard cards slows this card down a lot.
Galarian Zapdos V:
Fighting Instinct is great in a meta dominated by Pokémon V and Pokémon VMAX. I could see this card as a tech in Rapid Strike Urshifu VMAX decks and as a Fighting attacker in Aurora Bronzong decks that aim to hit several decks for weakness.
Passimian:
Since this is a Rapid Strike card it can be searched out with ease using Octillery or Sobble. Throwing Coach is a build-in Telescopic Sight that can be used on top of this tool to hit benched Pokémon V (incl. Pokémon VMAX) for an additional 60 damage. I can see this card as a one-off or even a two-off stable in Rapid Strike Urshifu VMAX decks and it also combos well with the new Zeraora V from the next set. Combined with Telescopic Sight Passimian allows Rapid strike Urshifu VMAX to hit the benched Pokémon V for 180 damage which adds up to 360 damage provided that you can choose two Pokémon V on the opponent’s bench. On the other hand Zeraora V can hit one benched Pokémon V for a total of 220 damage which suffices to knock out Pokémon V in one hit.
Galarian Moltres V:
Aura Burn is a decent attack on a Basic Pokémon V that can accelerate to itself from the discard. It can also be used in combination with Energy Switch to speed up other Darkness type attackers.
Galarian Slowking VMAX line:
The main selling point from my point of view is that Max Toxin bypasses all currently available blockers such as Zamazenta V or Decidueye since the main damage comes from poison which can be boosted with Toxicroak who also looks like the ideal partner for this Pokémon since you can use Galarian Moltres and Energy Switch to fuel Galarian Slowking VMAX instead of Houndoom. The first attack on the Basic Pokémon V is also decent since it helps the deck to set up.
Seviper:
Combined with Single Strike Energy Strength Tail can hit for a decent 220 damage for no more than two Single Strike Energy accelerated by Houndoom if you used a Single Strike Supporter this turn. I could see this card as a secondary attacker in non-V single strike decks that can also play Bruno. The main non-V single strike deck that comes to mind here is Single Strike Urshifu with Houndoom. The deck in essence plays similar to current Single Strike Urshifu VMAX decks with the exception that it is purely non-V-based, benefits a lot more from Karen’s Belief, and focuses more on Pokémon search cards.
Spiritomb:
This little fellow is Oricorio reloaded with the former Karen card mixed but this time it only affects the opponent’s discard pile. This card is a hard counter to Mad Party which can be seen as a weakness of Single Strike Urshifu VMAX decks. At first glance Single Strike Urshifu VMAX did not receive much support in this expansion sub-set unlike Rapid Strike Urshifu. However Spiritomb, despite not being a Single Strike or Rapid Strike card itself can be used as a great tech card in Single Strike Urshifu VMAX decks to counter one if its weaknesses.
Single Strike Urshifu:
With the release of Battle Styles Pokémon tried to sell us VMAX and non-V decks for both Rapid Strike and Single Strike. The front man of the latter was intended to be Primeape but he is much more complicated to use that Single Strike Urshifu. Provided that you have two Houndoom on the bench Single Strike Urshifu can attack for a single manual energy attachment and hit for a solid 240 damage. This suffices to knock out almost all Pokémon V and you can increase the damage output with Karen’s Belief. Being a stage one may make it harder to stream this Urshifu but this is where Seviper can come in. In this deck you do not expect the Pokémon to last for more than one turn. Therefore Bruno and Karen’s Belief can be used which can both be retrieved from the discard with Welcoming Lantern. Urshifu VMAX has shown that setting up two Houndoom in addition to a main attacker is not that hard to do. From my point of view this deck seems at least viable.
Zangoose:
Gale Claw is a nice attack which can benefit from both Passimian and Telescopic Sight. However, unlike Seviper the number of Rapid Strike supporters that are currently viable is more limited. The only ones that come to mind are Korrina’s Focus and Mustard. The latter one is trickier to use than the former. For these reasons I cannot see a deck build around it but Zangoose could be used as a decent one-off tech in Rapid Strike sniper decks.
Welcoming Lantern:
This is in essence a VS Seeker for Single Strike supporter. I can see this as a two-off or a three-off card in non-V Single Strike decks since they have a better arsenal of Single Strike supporters that can be used.
Echoing Horn:
There is not much that needs to be explained about his card. You can search it out with either Octillery or Sobbles evolutions from the first Sword and Shield set. A lot of our current decks run consistency Pokémon such as Dedenne GX, Crobat V, or Krickertune V. All three of them can be retrieved from the discard to be knocked out by the main attacker of the deck using Echoing Horn for an easy two or even three prize card swing. The only way to counter-act this item card is to ensure that your bench is always full. You can even bench an evolving non-V Basic Pokémon from the opponent's discard and snipe it out two Quick Shooter to draw an additional prize card. From my point of view this is easily one of the best cards in this set and most likely one of the best trainer cards in the current Rapid Strike arsenal.
Karen’s Belief:
Twenty more damage for Single Strike Pokémon for each prize card the opponent has taken is insane. Provided that Single Strike Urshifu VMAX is already able to knock out most Pokémon VMAX in one hit on his own with Single Strike Energy this benefits non-V Single Strike decks the most. I can see this card as a one-off or even a two-off stable in non-V Single Strike decks.
Dyna Tree Hill:
A stadium which prevents healing is great. Since the main source of healing at the moment is Cheryl and Mallow and Lana this is a direct counter to decks that either run these cards or at least base part of their strategy on healing and tanking. The main deck that fits this description at the moment is Corviknight VMAX Bronzong. However we have to keep in mind that Dyna Tree Hill is a passive stadium that acts on the opponent’s turn and also prevents yourself from healing your own attackers. It is therefore partly under the opponent’s control.
The entire set is an expansion set which aims to improve existing decks introduced in the last main set. I feel that Matchless Fighter actually succeeds in achieving this aim. Particularily Rapid Strike Urshifu VMAX gained a lot in this deck. The only cards in the above list that i would consider questionable or at least debateable from a competitive point of view are Hatterene, Beedrill and Zangoose.