This is basically the ruleset or criteria I base my movesets off of this will be short just to give better understanding on what I'm saying.
Attack and Defense: 100% is the base percentage I expect you to K.O or be K.Oed at any higher or less your power and weight is determined by this. I always go by 10% not 5% or any random numbers just be straight forward and simple as possible. This is also asuming your opponent is at 100% Attack and are hit at center stage no DI.
Knockback: I go by 5 types I'll explain each in order they are Weak, Medium, Strong, Powerful and Devastating.
Weak: These are usually moves that lock in place like a rapid jab, combo into self/starter, throw or a very weak projectile. it has very weak K.O potential.
Medium: Usually a finisher of a rapid jab, Neutral or Up Aerial or Tilt a simple get off me move probably won't K.O on stage unless their above 50% their weight and did not DI properly but should be decent for edge guarding off stage it can K.O.
Strong: This has decent K.O power it's the 3rd one so right down the middle. Moves like a Bowser side tilt, Fast uncharged Smash Attacks, Spikes, most Special Moves like a (Falcon Kick) or (Arm Rotor), sweet spot moves like Falcon's Knee or Zelda's twinkle toes or every character not named Little Mac's Back Aerial I'm not sure why everyones back air K.Os only time it won't is if it's stale like a Donkey Kong or Mewtwo can literally combo into itself.
Powerful: These are usally going to kill almost guranteed. for slower moves like a Smash Attack charged, really slow attacks like a Ganondorf up tilt, powerful Special Moves like a (Falcon Punch), Samus' OP (Charge Shot) it's basically a long ranged smash attack with the power it has and weaker Final Smashes.
Devastating: These are rare to see thrown out but if hit by one that stocks pretty much over. Moves like an Ike Forward Smash, a regular fully charged smash attack, Special Moves like a (Warlock Punch) and most Final Smashes have this amount of power if they are lacking in range the types where if you miss the entire move just fails.
Speed: I usually base Speed off a certain character that moves the way the character I made is closest to in the game right now.
Jumping: Jump height is pretty obvious if it's like Freya Crescent shes going to jump high like Falco she's a Dragoon, a Gabriel Belmont however is about normal height Mario and then someone that obviously sucks at jumping like a Shantae will be the lowest Little Mac don't think I have one that has more than 2 jumps like Kirby but that could change.
Air Speed: Basically if a character should fall like a feather a Floaty which I prefer or drops like a brick fast faller like Fox. I make comparisons for all 3 Ground Speed, Jump Height and Fall Speed.
Tap/Held Moves: If you haven't noticed all my characters have a regular and held version for a more powerful attack on ground and aerial moves like fighting game types like Ryu have. I think the only way Smash can evolve is if you add held moves to all characters like a Zelda for example is very restricted with her aerials Front, Back and Down air require very strict timing for her twinke toes to actually launch or it's just going to poke them. Adding variations like this to characters that lack a certain type of move like if they dont have horizontal range, an area attack in a certain direction or like a Bowser no spike without risking killing yourself this could solve.
That's all hopefully this gives a better understanding