: I think Doc can hang in there with Bowser despise of him having range, power, ground speed, and being heavy; However, Doc can also kill, combo, and edgeguard. Boswer can get comboed easily because of his large size, and being heavy. Doc's ko set ups work on Bowser as well. Bettter air game and get Bowser juggled as well, but Doc's juggled too. Stages with platforms work for Bowser since he's big.
: Zero suit Samus is a tough cookie because of her mobility and range; However, the Doc has both power and punishing game. She can also snipe his appoarches both the ground and in the air since he's slow on both fields. Not only Doc is kinda combo food for her due to his weight and falling speed, but gimpble because of his linear recovery. Doc can also get juggled by her with up smash, up air(to boast kick if he's hit), since she's tall and he's out ranged in the air. What the Doc has on Samus, lets see. If she miss a grab, free punish for endlag and Doc's grab is better. Samus can die easily from Doc's attacks since she's light. Some combos might work on Samus because of her height and he can also break out of her combos with n-air and jump punch. His cape helps against her projectile. Aviod Battlefield, Lylat Cruise, and Dreamland because Samus can use the platforms to her advantage to juggle Doc because of her tall height, mobility, and up smash, short hop n-air, up-air, and z-air.
:Stages with platforms are bad for little Mac because he can't do anything about it due to his bad air game. Doc's edgeguarding game beats little Mac because of his bad recovery and being light. Mobility to the ground for Little Mac, but Doc's ko options are stronger than little mac(even with ko punch).
:Even match. Doc: Power, better edgeguarding, better punishing game, and defensive playstyle. Mario: Mobility, combo potential, better recovery, and rush-down fighter.
: Appoarching with Doc isn't a cakewalk because of his slow mobility and Villager's ability to camp him. Doc has to aviod recovering low or else he's knock out by a bowling ball. N-air I think with Villager can break some of Doc's combos. Doc's ko potential and punishing game is better along with the cape to aviod camping. Villager's ledge game is good against Doc because of the tree, bowling ball, and up smash(if he rolls).
:For Lucas, I'll have to find good Lucas players to face if I'm lucky and my info wouldn't help, but I may have an idea about this MU. Lucas's mobility both in the ground and air is better than Doc, as his appoarches and his z-air to stop Doc's air appoarches. Lucas's recovery is superior to both Doc and Ness because of his z-air ledge grab and better PK thunder, but still gimpble though since Doc has the cape and tornado to add along with his edgeguarding game. Doc's ground game is superior because of better tiles, jabs(along with set ups) and smashes along with his ko potential.
For Lucas, I'll have to play him some more and face some more lucas players because I don't know if the MU even or who's favor. However for the rest above, I have my share of experience since I'm a Doctor main along with Mario, so I hope this helps.