I'm not sure if being a "casual" player means you want advice for in-game or competitive play, but I'll answer assuming your main concern is about competitive play. In that case, let me introduce you to the massive threat and offensive powerhouse that is Bisharp. I'll go through some of its better qualities and also some of its shortcomings that may turn you away from using Bisharp.
- Bisharp has earned itself the place as OU's premier user of Sucker Punch. Sucker Punch allows it to move before a multitude of threats and KO them or pick off weakened threats. Coming off its base 125 Attack stat, the move hits very hard forces tons of switches, which can allow you to make double switch plays that shift momentum in your favour. The move gives you insurance against a number of set-up sweepers if they're in range of the attack.
- Bisharp's Sucker Punch means it can be a brilliant win condition and late-game cleaner, especially considering how good Dark moves are in the OU metagame due to its lack of switch-ins. Bisharp carries Iron Head to punish Fairy Pokemon that attempt to switch into its Dark attacks. Swords Dance sets can extend Bisharp's sweeping prowess.
- Bisharp is also very well known for its ability trap Pokemon such as Gengar and Latios using Pursuit. Double switch plays and revenge kills support the use of Pursuit immensely. As Bisharp forces a lot of switches due to Sucker Punch, you can also use Pursuit instead to make an aggressive play and potentially knock out a Pokemon before it switches.
- Bisharp receives access to STAB Knock Off, which can be tricky to deal with as there's often to way to avoid losing an item. It's especially good on Bisharp as there are few Pokemon in the game that can resist Knock Off and beat Bisharp 1v1 at the same time as it has options to hit Fairy Pokemon.
- Bisharp is a good check to several Fairy-type Pokemon thanks to Iron Head, most notably scaring off basically any variant of Clefable. Sylveon also does not appreciate the attack.
- Swords Dance Bisharp is not only good as a late-game cleaner, but also as a stallbreaker. Bisharp can freely switch into Toxic and threaten the opposition with Swords Dance which make Knock Off very difficult to switch into; at the very least, something will lose its item. Lum Berry can be used to save Bisharp from burn and paralysis that tend to be common on stall teams.
- Bisharp's Defiant ability is more useful than it seems. Defiant means Bisharp's very presence discourages the use of Defog as it risks giving it a free boost. This is especially notable as many of OU's Defog users are either weak to Bisharp or can't do much to it and lose 1v1. Intimidate users, notably Landorus-Therian (which otherwise checks Bisharp), translate only into a free Attack boost and potential kill with Sucker Punch.
- Bisharp can be highly unpredictable due to the variety of different sets and items it can use. Life Orb, Lum Berry, Assault Vest, Choice Band and others are all viable options of Bisharp. Black Glasses are also extremely common and rather annoying to face as they don't reveal Bisharp's item to the opponent, useful to bluff a Lum Berry or Choice item if Life Orb is not revealed. Due to its multitude of different sets, Bisharp can pick and choose what it beats; with Assault Vest, it can freely switch into attacks from special attackers, especially Draco Meteor from Latios who is rarely a good play if Bisharp is in the back. With Life Orb or Choice Band, it lands more KOs and OHKOs a lot more Pokemon from full health, especially after Stealth Rock.
- Bisharp's defensive typing, though weak to three very common attacking moves, packs eleven resistances and means Bisharp has a good amount of switch-in opportunities. Though its special bulk leaves much to be desired, it is no slouch in physical defence and absorbs resisted physical hits easily and with no investment.
- Bisharp has some nifty other options that can catch opponents off-guard. Taunt can be used to make Bisharp a full stallbreaker and could be very useful on the higher ladder where skilled stall users tend to hang out. Low Kick could be useful as a lure for Bisharp checks such as Ferrothorn or Heatran, which can't switch into the without being knocked out by it. Aggressive plays are usually required for it to be useful, however.
Though Bisharp has a wealth of different qualities and traits that have made it popular in OU, it also has some flaws that must be consider when using it.
- Sucker Punch is not always a fail-safe play and can end up in risky situations where the opponent has a non-attacking move they can use in an effort to stall Bisharp of its PP. Either player could come out with an attacking move at any moment. which would end in either player's favour. There is no escape to this and often no way to guarantee that you'll come out with a kill or an advantage.
- If the opponent pulls a status move or setup move against your Sucker Punch, you could be left in a very bad position. Sucker Punch can easily end up as a risky mind game and toss up between risk and reward.
- Bisharp is weak to Fire and Ground and very weak to Fighting. These are some of the most common attacking types and are often used as coverage on Pokemon, which means Bisharp can't always switch in based on its type matchup alone. A Fighting weakness makes priority such as Mach Punch especially problematic.
- Knock Off does worse against Mega Pokemon whose items can't be removed. Without Knock Off as a nuke, Bisharp often can't do significant amount of damage to the opponent and ends up as setup fodder for Mega Scizor, Mega Sableye, Mega Gyarados etc.
- Bisharp has issues against Substitute which can put it in an awful position if it's used against Sucker Punch.
- Non-Lum Berry Bisharp hates status, especially burns which effectively shut it down for the rest of the game besides the ability to remove items. The omnipresent Scald and popular Will-O-Wisp make Bisharp's role more difficult.
- Dark and Steel have good neutral coverage but limited ability to deal super-effective damage. Bisharp has particular trouble against bulky Water Pokemon and tank Garchomp who can absorb hits and respond with a threatening move. Some Pokemon such as Azumarill can take the opportunity to set up.
- Bisharp is fairly slow and not difficult to scary away with a Fire, Ground or Fighting attack that you likely have left on your team. Its frailty on the special side outside of Assault Vest can be easily exploited with a powerful STAB move. Be wary that it can still deal some extra damage with Sucker Punch.
Bisharp, though lacking in Speed and special bulk, is a potent Sucker Punch user with tons of utility to offer its user and an ability to fight against teams of all playstyles. Its access to some of the most controlling attacks in the game, Knock Off and Pursuit, combined with STAB on both means it is adept at applying pressure and dealing damage. Though its vulnerability to common attacks and its dependence on Sucker Punch to fight offence can sometimes hold it back, Bisharp is a big threat in the game and one you should definitely consider raising or using on your team.