Alright, here are my opinions on what Pichu: M should have. I made this without access to hit-box data, I only had SDM's frame data and my own knowledge as a resource, so a few parts might be a bit wrong. These should be considered seperate ideas, not a package. It is entirely fine to incorporate one idea and disregard another, the character would still work.
• Jab
-Hits on frames 2-3.
- Electrified (frame 3 only): Release a small electric shock in front of Pichu. Electrified jab deals 0.5% recoil, has 1 frame of stun, is treated as a projectile with transcendent priority and deals no extra damage or knockback.
-Disjointed hit-box in front of Pichu.
REASON: Accentuates it's strengths (lock ability) and slightly improves it's weakness (poor range).
• F-tilt
- Electrified (frames 9, 10 and/or 11 only): Electrified F-Tilt deals 2% recoil, has set knockback similar to that of Reflector (able to semi-spike) and deals no extra damage.
-Disjointed hit-box in front of Pichu.
REASON: Gives Pichu a decent GTFO move outside of Nair.
• D-Tilt
-Hits on frames 5-9.
- Electrified : Electrified D-tilt deals 1% recoil, has a vacuum effect similar to Dr. Mario's D-tilt, but much weaker, and deals no extra damage.
-Hit-box on tail tip is larger.
REASON: Just a slight buff to combo ability.
• U-Tilt
-Hits on frames 5-14.
-Electrified (frames 12, 13 and/or 14 only): Electrified U-Tilt deals 1% recoil, has a vacuum effect similar to Dr. Mario's D-Tilt, but much weaker, and deals no extra damage.
-Hit-box on tail tip is larger.
REASON: Again, slight buff to combo ability.
• U-Smash
-Hits on frames 7-11.
-Hit-box extends further horizontally to both sides (not disjointed).
REASON: Slight buff to kill ability.
• D-Smash
-Has 39 frames total.
-Electrified: Electrified D-Smash has 6 hit-boxes (on frames 6-7, 9-10, 12-13, 15-16, 18-19 and 21-22) which trap opponents similar to Pikachu's down smash, deals 0.5% recoil per hit-box, 'B' can be released at any time to deliver the last hit of non-electrified D-Smash (automatically delivers this hit on frame 24 if 'B' is not released) and each hit-box deals 2% damage.
-Hit-box extends further horizontally to both sides (not disjointed).
REASON: Makes Dsmash useful.
• F-Smash
-Electrified: Perform Melee version of move.
Non Electrified: Pichu performs animation but deals no recoil, damage or knockback.
REASON: Allows Pichu to actually kill with it through feinting mind-games and de-electrifying it during the attack to mess with the opponent's DI (the main thing that ruined this move).
• Dash Attack
-37 frames total and is IASA frame 32.
- Electrified: (frames 14, 15 and/or 16 only): Electrified Dash Attack knocks opponent into the air (similar to Fox's dash attack), deals 2% recoil damage, and deals an extra 2% damage.
- Hit-box extends further in-front (not dis-jointed).
REASON: Lets Pichu reliably finish combos with it and possibly start a juggle.
• N-Air
-Electrified: Electrified N-Air deals 1% recoil, deals 1% damage and has 0 knockback.
-Larger hit-box.
REASON: Gives him a gimping tool and adds to combo ability.
• F-Air
-Electrified: Perform Melee version of move.
-Non Electrified: Acts like a horizontal drill (similar to most character's F-Air in Smash 64 like Fox and Luigi).
-Larger hit-box.
REASON: Nice all purpose multi-hit attack.
• U-Air
-Electrified (frames 4 and/or 5 only): Electrified U-Air deals 2% recoil, has small spiking hit-box on the very tip of tail [actual spike, not semi-spike like Pikachu (however, it does have the same angle as Pikachu's semi-spike U-Air)] and deals no extra damage.
REASON: Gives Pichu a new kill move and combo finisher.
• D-Air
-Hits on frames 6 to 26.
-Electrified: Perform Melee (electrified) version of move.
-Non Electrified: Acts like a Drill (similar to Fox's/Falco's/Jigglypuff's/etc...'s D-Air).
REASON: Buff to combo ability with the drill and gives another approach option.
• B-Air
-Electrified: Electrified B-Air acts the same as electrified (Melee) Fair and deals 4% recoil.
REASON: Lets you combo when opponent is behind you instead of having to finish the combo right then and there.
• Thunder Jolt
-Comes out frame 15 and projectile lasts 110 frames.
-Transcendent priority.
REASON: Just an overall buff.
• Skull Bash
-Deals no recoil damage.
REASON: Lets Pichu recovery without damaging himself.
• Agility
-Deals no recoil damage.
-Can be cancelled exactly like Pikachu's Quick-Attack Cancel (QAC).
-Still has 1 frame of 'landfallspeciallag' at the very end of the move, allowing for Perfect Agility landing and dashing.
REASON: Again, recovery without damage. Also makes it a great movement tool because of QAC and Perfect Agility.
• Thunder
-Aerial Thunder is jump-cancellable on frame 20.
REASON: Lets Pichu better combo from Thunder and keep the opponent in the air.
• Grab
-Grab-box extends behind Pichu.
REASON: Slight buff, Pichu often ends up facing away from the opponent right next to them and has few tools to hit them.
• All Throws
-If 'B' is held down, electrify move. Electrified throws deal a small amount of extra damage while Pichu is throwing (no damage post-release) and deal 1% recoil.
REASON: Simple buff for extra damage.
• Falling Speed
-Around the same speed as Melee Ganondorf.
REASON: Lets him SHFFL better.
• Weight
-Around the same as Melee, PAL Fox.
REASON: Makes him slightly more difficult to kill.
• Ledge and Get-Up Attacks
-Electrified: Electrified get-up attacks deal extra horizontal knockback and 1% recoil.
REASON: Another GTFO move to compensate for how easy Pichu is to tech chase.
ELECTRIFY MECHANIC DESCRIPTION:
Any attack that can be 'electrified' (Jab, Tilts, Dash Attack, Aerials, Fsmash, Dsmash, Throws, Get-Up Attacks and Ledge Attacks) will be non-electrified by defauly. You can electrify the above moves by pressing or holding the Special Move button while performing them.
You can electrify seperate parts of the move by releasing 'B' on any frame you don't want electrified, and pressing it on any frames you do want it electrified. Some attacks can only be electrified on certain frames (you don't need to press it on these specific frames, just holding it before hand and waiting will still work).
Electrifying deals re-coil damage (different for each move) and increases the size of the hit-box of the attack slightly.
FOR SPELT: YOU DON'T HAVE TO ELECTRIFY MOVES AND IF THE MOVE ISN'T ELECTRIFIED IT DOESN'T DEAL RECOIL.