Score isnt really relevant at all to the speedrun community. Currently, I'm the only person doing runs for single segment highscore and sinister1 has also done it in the past. There are a few people interested in IL scores, but its a long process to learn. A very different beast to tackle compared to the speedrun.
There is an incredible amount of RNG in the game, 9/14 fights have random stars that you can get, and while most of them are about 50%, Don Flamenco 2's random stars are 6.25%, so in real time attempts, its not even worth going for them. Almost all the fights have random amounts of HP the opponents will get up with, and some opponents have random KO's which means you get far less points if they decide not to get up. You may notice on Bald Bull 1 he only does a couple of Bull Charges for the whole fight. This is because I either knock him down, or take a knockdown as the clock ticks over a specific time which triggers the Bull Charge pattern, this is not easy to do in real time as Bald Bull can give you patterns where trying to skip the charge is incredibly difficult or even impossible. I hold the current record for playing in real time with a score of 266,450 (
https://www.youtube.com/watch?v=Y4JIcBABN8E if anyone is interested) you may notice that there are 2 losses in the run, this in an artifact from the Twin Galaxy ruleset, I am however trying to beat this record with 0 losses which is alot tougher than I realised when I started.
boct1584 has pretty much covered the point system, just the regular knockdown is 1010 points (1000 for the knockdown + 10 for the regular punch) other than that, its all correct.
I have no idea how long maxing out the score on Soda Popinski would take, firstly you have to do the clockstop glitch, then intercepting his hooks with face punches, which deal 1 damage each. when Soda gets down to 1hp (lets assuming Mac is at 17 HP) Mac would get hit with a straight jab, getting hit with a punch allows the opponent to recover 4hp, the straight jab does 16 damage to Mac bringing his HP down to 1, I would then intercept 4 hooks with a face punch which deal 1 damage each and recover 4 HP each time bringing Macs hp back up to 17, as long as you have the clock stopped, this process can be repeated over and over. Mac would lose his hearts eventually and it takes about 10 second each time to get his stamina back.
Also along with this, opponents do not recover HP to full when Mac gets hit, instead there is a 'soft' cap of 32 (if opponent is at 32hp and hits Mac > do not recover hp, if opponent is at 31hp and hits Mac > recover to 35hp). This is true for all fights except 3, King Hippo's soft cap is at 16, and Don Flamenco 2's and Mike Tyson's soft cap are at 48. All opponents including Mac start with 96hp.