This list was made on 4/15/18. The Metagame right now is Hard Hitting attacks.
Helpers: deadlock1800 and ginosweet1 and Citrus_Gaming4!
If there are any reasons why characters should move on the tier list, show me why.
[SS]Ice Climbers- They can both use their spin attack against someone with lots of damage done! The Icie's recovery is great!
[S]Link- Gale Boomerang is a high damage move if used next to another player!
[S]Rosalina- Luma Shot is OP if you charge it for 4 seconds and DON'T GET HIT!
[S]Meta Knight- Just like the Ice Climbers, Meta Knight has Mach Tornado which if used by another player, deals a lot of damage and a big hitbox!
[A]Wario- Wario Bike is like Spin Dash and Wario Waft can instant kill but has a bad recovery.
[A]Yoshi- Yoshi has Egg Roll which is just like Sonic's Spin Dash, Yoshi was put here because of his lack of recovery. Egg Lay to Egg Roll = True Combo
[A]Sonic- His Spin Dash attack has been nerfed a lot. It can still wipe people out, but it takes more effort. It also has a 2 second cooldown!
[A]Toon Link- Like Link but Boomerang does decent damage. It's like a nerfed Gale Boomerang but Hero's Bow is OP because it is a projectile with no cooldown and does a ton of damage.
[A]Cloud- Blade Beam is a good projectile and Cross Slash is OP. Limit Charge 100% can let you one-shot with Cross Slash and have greater recovery.
[A]Master Hand- Finger Bullet is a average projectile and Flying Slap is a REALLY GOOD attack that can one-shot someone if used right.
[A]Peach- Parasol is a very good spammable, damaging move.
[B]Palutena- Autoreticle is good when near players and Warp is like Mewtwo's Teleport.
[B]Charizard- He has Flare Blitz which insta-kills someone but does Recoil. He also has a great recovery.
[B]Robin- He has a good combination of Projectiles, Melee, and Life Stealing.
[B]Roy- He is a clone of Marth but Flare Blade can instakill if charged enough. Double-Edge Dance is OP if used next to someone, and you can chase the enemy whie using it!
[B]Kirby- He can fly for a long time which is useful when timing people out, he can use Inhale which can bring you OP attacks.
[B]Mr Game and Watch- Judge is a very good attack with 7 giving a health item, 8 giving a freeze to the enemy, after doing that, keep using judge. You might get a 9!, 9 insta-kills! It is spammable and you can chase people while spamming it! Also he has a very good recovery.
[B]Marth- Dancing Blade is a good multi-damaging attack.
[B]Mewtwo- Shadow Ball is a good charge projectile with decent damage. Teleport is OP! You can go almost everywhere with it and it has a 1 second cooldown!
[B]Venusaur- Bullet Seed is good for kinda close range attacks and Razor Leaf is a good melee attack. Vine whip is too. Synthesis is good for camp-healing.
[B]Blastoise- Withdraw is very decent for a melee attack and Protect is good against Sonic and other multi attackers. Waterfall is good for attacking too!
[B]Pit- Palutena Bow is a VERY HIGH DAMAGE projectile with a small cooldown.
[B]Lucas- PK Freeze is really good for freezing people.
[B]Inkling- Splattershot is good for mid-range attacks and Squid Swim can help you run away from people and Splat Bomb is good for a trap!
[B]Greninja- Water Skuriken is good for mid range. Shadow Sneak is good for melee damage.
[C]Luigi- Like Mario, Luigi's Super Jump Punch is the same as Mario's Super Jump Punch, but Luigi's Green Missle is good for using on people with almost no health and Luigi Cyclone is kinda good.
[C]Olimar- Pikmin Throw is good because it does good damage but it happens over time. His Winged Pikmin attack goes high.
[C]Rob- Arm Rotor is good when you use it near another player, and you can run with it! Gyro can do some good damage.
[C]Villager- Lloid Rocket is a good projectile with high damage and Balloon Trip is a awesome recovery. Timber instakills when it hits.
[C]Snake- Hand Grenade is a good projectile and C4 is good for trapping enemies!
[C]Bayonetta- Not as good as Smash 4 but yeah, Witch Time is good for trapping people then use Bullet Climax until they are not frozen.
[C]Rayman- Telescopic Fist is a good charge attack and Lockjaw is good for melee combat. Ground Pound is decent.
[C]Bowser- Flying Slam is a very high-damaging move with little cooldown.
[C]Ness- PK Flash is good for people next to you with it's high damage and it's high area but with high cooldwon. PK Thunder is not good for recovery, but for snipping.
[C]Ike- Eruption is a good charge attack with high damage. Counter is good for multihitting attacks like Spin Dash.
[C]Bandana Dee- Spear Throw is good and thier recovery is great! Parasol can be good for melee fights! But they are slow.
[C]Corrin- Dragon Fang Shot is a good projectile and Draconic Ascent is a great recovery move. Dragon Lunge can be a great getaway option!
[C]Lucario- Aura Sphere is a good Charged Projectile.
[D]Wii Fit Trainer- Sun Salutation being charged is decent and spammable. Super Hoop has good kill power.
[D]Samus- Her Charge Shot can be deadly, and Bomb is also a good move to use. Missle does decent damage.
[D]Diddy Kong- He has Monkey Flip which can be good for recovery and attack. Rocketbarrel Boost is a great recovery if charged up enough.
[D]Mario- You can use the Super Jump Punch next to people for high damage, but you are vulnerable on the way back down. 
[D]Paper Mario- Hammer is good for melee after using Flip to knock people over. Paper Plane is great for recovery and running away!
[D]Bowser Jr.- Average attacks and Clown Kart Dash is great.
[D]Slippy- Booster Pack is the only attack that deals good damage.
[D]Captain Toad- Super Pickax is good for melee and he has a great recovery!
[D]Roblox- Skateboard is decent and Bomb is damaging. [I didn't know this] Balloon is supposed to be used right before your second jump so you gain great height. [My mistake.]
[E]Pacman- Bonus Fruit is decent and Fire Hydrant can help with blocking people.
[E]Ganondorf- His Warlock Punch insta-kills and Wizard's foot does decent damage.
[E]Captain Falcon- FALCON PUNCH!!! one shot btw and average cooldown.
[E]Ridley- Spitfire is almost usless and all of his other moves launch you off stage which is bad.
[E]Little Mac- He isn't too good because his attacks usually miss or don't do any damage at all. Slip Counter is good. Straight Lunge and Jolt Haymaker are good attacks and mobility options.
[E]Ryu- Hadoken is decent and his side B is good. Shoryuken can be a decent melee attack.
[E]Ninten- Just a clone of Ness but PK Beam is worse than PK Flash.
[E]King Dedede- Inhale is good for knocking people off the stage, and Jet Hammer is good. His recovery is bad. Gordo Throw does decent damage if it hits.
[E]Shulk- Even with Monado Arts, Shulk is a weak attacker.
[E]Donkey Kong- You can one-shot a player with Headbutt but that is rare. Spinning Kong doesn't really do much.
[F]Megaman- Charged Blade is a good projectile and Leaf Blade is good when used near players.
[F]Peppy- Blaster is decent. Barrel Roll is difficult to land. Bunny Hop does good damage when near people. Accele-Reflector is like Fox's Reflector.
[F]Pikachu- He has average attacks and Thunder is good.
[F]Dixie Kong- It's Diddy Kong but worse recovery and has barely any strength.
[F]Zero Suit Samus- She has Plasma Whip which is good near people and Flip Jump and Boost Kick are good recovery options.
[F]Zelda- Phantom Slash is decent. Nayru's Love is decent.
[F]Falco- Pretty much Fox but Fire Bird does decent damage.
[F]Fox- He can use Fox Illusion to run away from people, Reflector is a good wind-box attack.
[F]Jigglypuff- Rest one-shots a player near you but it is very high-risk as the cooldown is very long and now if you use it on the ground you cannot jump during it anymore.
[F]Duck Hunt- Trick Shot? More like, CAN'T HIT. Clay Shooting is average. Wild Gunman does good damage.
[F]Shiek- Bouncing Fish never hits anyone and has a long cooldown, Burst Grenade is decent. Vanish is a good sneak away option.