Centaur Warrunner is a Strength hero who is mainly played as an Offlaner.
The main problem with Centaur Warrunner derives from the abilities' cast range, which requires Centaur Warrunner to be virtually on top of the enemy hero to be useful. This includes Hoof Stomp (Q) and Double Edge (W), abilities that stun surrounding enemies within a 350 radius and damage enemies respectively. This forces Centaur Warrunners to purchase the Blink Dagger to provide value to the team, but by rushing Blink Dagger, Centaur Warrunners may become too squishy before becoming useful or effective in disabling enemies.
Centaur Warrunner's Retaliate (Pbuttive Ability E) is easily countered by Silver's Edge, and Stampede (Ultimate Ability R) can be easily dodged with commonly purchased items such as Force Staffs and Euls' Scepter of Divinity, as well as countered by enemy abilities that stun or root.
Dazzle is an Intelligence hero who is mainly played as a Hard Support.
Dazzle's abilities in the current meta are simply overshadowed by similar heroes that do the same job as him (Oracle *wink wink*). Poison Touch (Q) is alright early game, providing ample poking and killing potentially during the laning and early-to-mid phase of the game, however, it requires Dazzle to constantly right-click enemies to provide the slow debuff on enemies (make sure that you know how to disable auto attack in Dota 2!). Although his shard provides Dazzle with a hex debuff, it is easily countered by Black King Bars and Linken's Sphere.
Shallow Grave (W) is a pretty decent ability that provides the team with potential saves but is usually met with Axe counter-picks. Shadow Wave (E) is currently underwhelming for its mana-to-healing ratio. Lastly, Bad Juju (R) just does not do much for your team or against the enemy, and what it provides is just not worth your health in team fights.
Grimstroke is an Intelligence hero who is mainly played as a Hard Support.
Honestly, Grimstroke has a lot to offer within a single hero. He has a damaging slow, silence, stun, and debuff all with just his set of abilities. However, he is a good example of being a jack of all trades.
Stroke of Fate (Q) is an unreliable slow, where players would need to predict where enemies would be, so if you can't aim, this ability loses all its value. Phantom's Embrace (W) sends a phantom to latch upon an enemy. Once latched onto an enemy, it silences the enemy, but the silence is immediately canceled if the phantom is killed (by right-clicking). It may work in lower MMR brackets, but once players are more skilled and knowledgeable about the game, Phantom's Embrace becomes an easy skill to counter.
Ink Swell (E) is just such an unreliable stun - either you become the deliveryman for the stun, or you would have to rely on a teammate that can jump in front of the enemies for you. Lastly, Soulbind (R) is an ultimate that binds a targeted enemy hero that is closest to its teammate, and all single-target spells are applied to both enemy heroes. Sadly, this may be one of the only positive abilities that Grimstroke may have.
Kunkka is a flexible Strength hero who can be played as an Offlaner or Mid.
Kunkka is a rather niche hero who has a skill ceiling that requires players to properly time his abilities.
Torrent (Q) is usually a setup to Ghostship (R) for huge damage and chain stunning. If pulled off perfectly, the combo does a total of 920 damage (excluding debuff and talent bonuses). The tricky part comes in timing Torrent, Ghostship, and X Marks the Spot (E), where each of them has a delay before they come into effect.
With this delay, any fights near towers or outposts become turnable. Enemy teammates have the time to react to Kunkka's abilities, such as applying Force Staff pushes and Lotus Orb shields on the focused target.
Slardar is a Strength hero who is mainly played as an Offlaner.
Slardar's main problem is similar to Centaur Warrunner - he requires a Blink Dagger to initiate and land Slithereen Crush (W) and Bash of the Deep (Pbuttive Ability E). This Blink Dagger requirement slows down Slardar to become a functional team member as Offlaners are usually suited to buying aura items for the team, so it is best to ensure both supports can cover for what is lacking in the team.
While Guardian Sprint (Q) provides Slardar with extra movement speed and health regeneration, it is only advantageous in the river, or his water pool that comes from the upgraded Aghanim's Scepter Slithereen Crush or Corrosive Haze (R). Unfortunately, most fights happen outside of the river, and Guardian Sprint can be countered with abilities that slow, stun, root, or hex, which are part of common ability kits that meta heroes possess.
Corrosive Haze (R) can be a good solution to invisible heroes like Riki and Bounty Hunter, however, to maximize its utility, you will have to coordinate with your team for a physical carry. Another small disadvantage with Slardar is that he cannot take Dota 2 stacking camps quickly, so support stacks lose their effectiveness.
Although there are a couple more heroes to watch out for, it eventually boils down to you and your team! Dota 2 developers always aim for balanced gameplay, so in order to win more games, gain an edge against your enemies by identifying Dota 2 worst items that you should avoid purchasing in your games!