Andy; with all the creative attacks he can have implemented with his wrenches and various different units straight from Advance Wars would hands down be the most interesting character from his franchise. Andy also has a very unique aesthetic to him that hasn't been used much in Smash Bros. I guess the closest to him would be Ness in terms of stature but even then Andy would be a bit taller and looks a lot different from the rest of the cast.
Andy's playstyle would be a blend of the summoner archetype along with unique wrench attacks that do more than just act like a sword; but also traps foes, catches items when timed right, and provides Andy great, quick options to use when he fights in close quarters.
Unique Attributes to Andy
Andy has a fund system very similar to how it works in Advance Wars. Andy starts off by having a certain amount of money at the start of the game but he needs to get more funds to use his units. By using his Down Special;
Building Capture, Andy can generate funds that will be displayed below his stock icons showing the amount of money he has. The longer the building stays active (it can be destroyed by the opponents), the longer Andy will continue to generate funds. Using these funds, Andy can use his Neutral Special;
Unit Purchase and he can buy various different land units by purchasing from a small sub-menu that shows the various different units he can purchase (Tanks, Anti-Air's, etc.)
Additionally, Andy has unique Codecs similar to the ones Snake had in Brawl where he can radio Nell, Max, and Sami about the opponent he;s facing. Nell would give Andy insight on the character he's facing while Max and Sami give additional insight and occasionally mock Andy. Other CO's from Advance Wars also give their insight to the character as well occasionally. Think of it as a blend of Snake's Codecs and Palutena's Guidance.
Melee Attacks
All of Andy's standard attacks are based are unique moves done using his wrenches as mentioned before with some exceptions here and there.
Entrance Animation: Andy comes out of an APC similar to how Lucas enters.
Idle Animation: Andy wields his wrench in his hand while holding his other below him very similar to his official AW2 pose.
Jab: Andy repeatedly jabs his opponents with his wrenches with both hands before giving a final thrust to end the series of jabs. Andy's jab can also be used to catch items with his wrench when timed perfectly as an enemy throws a projectile at him. I.e. if Peach throws her Turnip at Andy he can catch it by simply jabbing at the right time and then can throw it back.
FTilt: Andy quickly lunges his wrench at his foe doing small damage.
UTilt: Andy lunges his wrench in an upward animation to strike foes either on the ground or on the air. Can also be used to juggle opponents as part of a combo.
DTilt: Andy very briefly lunges his wrenches towards his opponents feet trapping them in the ground for a very short amount of time allowing him a follow up move.
Dash Attack: Andy throws one of his wrenches towards the opponent that lunges them in the air depending on how much their damaged.
NAir: Andy gets a rifle similar to the ones carried by Infantry units and fires shooting a few bullets that do mild damage.
FAir: Andy lunges his wrench forward that covers some distance similar to Marth's FAir.
BAir: Andy lunges any foes behind him backwards with his wrenches.
UAir: Like his Up Smash listed below, Andy spins his wrench multiple times in the air to launch his foes in their air for star/screen KO's.
DAir: Similar Cloud's DAir, Andy can use one of his wrenches to spike the opponent downwards sending them crashing to the ground. Great edgeguarding tool.
FSmash: Andy smashes his foes with his wrenches in a 1-2 punch fashion. First he lunges his wrench at his opponent that keeps them in place and then he uses his other wrench to do hefty damage that sends the opponent flying
USmash: Andy lunges his wrench upwards and spins it multiple times launching his foe in the air; similar to how King Dedede's Up Smash works. An effective kill move.
DSmash: Andy lunges his wrench downwards in a 360 motion launching any foes near him in the air. An effective way to punish players who roll frequently.
Grab: Andy grabs his opponent with one of his wrenches in their mid-section; stopping them dead in their tracks.
Running Grab: Same deal only he dashes while doing that.
FThrow: Andy uses a Recon unit to launch his opponent forwards as they keep getting hit for a while by the Recon in motion. Can also be used to hit other enemies also in the way.
BThrow: With his foe still trapped by his wrench, Andy launches his foe backwards with his wrench to send them flying.
UThrow: Andy summons a mech unit to shoot a rocket above him doing considerable damage to his foe that sends them flying upwards.
DThrow: Andy tosses his foe down to the ground and repeatedly smacks them with his wrench; sending them flying.
Specials
Neutral B: Unit Purchase. Using the money Andy has at the start of the match as well as generated from his Down Special; Building Capture, Andy can purchase various different land units from a small sub-menu with varying costs, (i.e. Tanks, Artillery's, Anti-Air's, etc.).
Side B: Bazooka. Referencing the Mech units from Advance Wars, Andy uses a bazooka that fires a quick, rapid missile at the opponent that's both quick and does mild damage (i.e. around 7-9% damage).
Up B: Battle Copter. Andy summons a Battle Copter to not only aid him in recovering to the stage but also striking opponents that are in front of Andy. Controlled for a few seconds (3-5) and is more powerful with Hyper Upgrade.
Down B: Building Capture. Andy captures a city (which he spawns out) and the longer it's used, the more money Andy will have generated that's displayed under his stock icons. It can be destroyed by opponents of course which will cut Andy's funding.
Final Smash: Hyper Upgrade/Megatank. Andy's CO Super Power from Advance Wars. Andy recovers 50% damage (referencing the fact that his CO Super Power heals 5HP to all his units in Advance Wars) and on top of that Andy summons a massive Megatank straight from Advance Wars: Dual Strike that has very powerful, rapid firepower which does massive damage & knockback to anyone that's in the way.
Other
Up Taunt: Andy positions his wrench towards the screen and lets out his signature grin.
Side Taunt: Andy gives the peace sign much like how he does in his winning animation in AW1; grinning all the while.
Down Taunt: Andy checks his tool box for utilities while also scratching his head.
Victory Animation 1: Andy throws his wrench in the air and grabs it, striking his AW2 pose.
Victory Animation 2: Andy climbs on top of an APC and gives the peace sign.
Victory Animation 3: Andy see's an Airport in the distance and asks "What's an airport again?" to the player; breaking the fourth wall as a reference to his infamous line.
Victory Theme