it's really hard to say which of the clones are the most silmar because every single move but throws are different for mario and dr. mario so dr. mario has better air speed. so what they in fact have in common 100% are the following: throws, grabs, pummel, WD, DD, height, falling speed, sheild and then EVERY THING about them is a little bit different from f-tilt to f-smash.
dr. mario's f-tilt is faster.
piachu and pikachu the following are the smae not counting self damage nor range ,but if there is a different use than it doesn't count. pummel, jab,f-tilt, d-tilt, jolt, all but upair(not counting the fact pichu has much less lag for all of them from 13 frames of lag to only 7 for bair) If you want to count the fact that that pichu's air moves for much faster and range than there is nothing the smae as them.
also pichu's fair would be totally different because he can legitly combo with it with more moves. and safer vs sheilds. like pikachu could safly fair peach's sheild and start jabbing the F*** out of it.
also something i'd like to note other than marth/roy all the clones seem to have at least one had a walljump. maybe for a bit of balnce I geuss.
also pichu is much more techical thann pikachu, more defenceive, better grab game, overall better air game, faster, harder to hit in everyway but range spaceing, harder time breaking walls, but small size makes it worlds easier than it is for bowser which more range.
pikachu better gimps, upwards kill power but lacks some of that side killing power, more range, worse defnce but more for offence, can take hits worlds better.