An easy and fast way for mastering 1 fighter and it should also work for mastering all fighters aswell.
For the 24h play time:
You can boost it with 2 different fighters at the time by choosing the Tag Team Practice mode. Select 2 different fighters that you want to boost and leave the game there for 24h. Go to sleep/work/school. After 24h, both fighters will have the 24 hours play time (You can check the progress in the Nekropolis). This means, that you can boost the 24h play time for all the playable fighters in ~13 days instead of 27 if you boost it 1 fighter at the time.
For the 100 victories and 150 X-Ray attacks (these two are counted for both fighters)
Make sure the round is set to 3 and time is set to off (no timer) in the Options.
This one involves using only 1 Kombat Kode (aka "cheating"), so if you are not into cheating, don't use Kombat Kodes but the trick remains the same, except it will take a little bit longer. Using a Kombat Kode will not void the achievement.
Choose 2 Players, then select Versus mode and choose Two vs Two mode (you will need 2 controllers). Choose 2 fighters, 2 that you want to boost, the others don't matter. Press Y and choose any arena where you can do a Stage fatality. Then start the fight.
At the loading screen, quickly enter the 466-466 code with both controllers using the X, Y and B buttons. This will enable the Unlimited Super Meter mode. With this mode, you can do unlimited X-Ray attacks until you win the round (you kill the other fighter).
To boost these 2 elements in one match, do the following steps.
For the first 2 rounds, use both boosting fighters X-Ray attacks until you win both rounds. I suggest switching fighters (press LB) when one of the non boosting fighter is out and use the other boosting fighter's X-Ray attack on the 2nd fighter. This way, you can perfom the same amount of X-Ray attack with both fighters. The match is not over yet because you have to win a 3rd round.
During the 3rd round, do the X-Ray attacks with your boosting fighters but don't kill one of the 2 fighters, leave a small amount of health. Use the 2nd controller to beat P1 (your boosting fighters). Repeat this above step 1 more time. Now the match should be tied (2 wins for each fighters).
At round 5 (final round), use the boosting fighters X-Ray attack again. At the Finish Him/Her! screen, perform one of the fighter's "-ality" and win the match.
Again, I suggest that you switch the boosting fighter (press LB) when one of the non boosting fighter is out for all 5 rounds. I managed to perform 13 X-Ray attacks with Kano and 15 with Raiden.
This method will also boost the 200 Versus matches.
Along the way, you will unlock the Finish Him?, Complet-ality, Ultimate Humiliation, The Grappler, Finish What You Start! and e-X-cellent achievements if you change characters between matches and if you do the 2 throws also.
For the 100 "-alities"
Set the round to 1 and timer to 30 secs. Choose 2 players, Versus, One vs One. Choose 1 boosting fighter, 1 random. Select an arena (with Y) where you can perfom a stage fatality. Start the match. At the loading screen, input the Sans Power code (044-440). 1 hit and the Finish Him/Her! screen should appaer. Perform the fighter's stage fatality. Rinse and repeat 99 times. Don't forget to input the code during each rematch.
For the 10,000 pints blood spilled.
Set the round to 3 and timer off (no timer). Choose 2 players - Versus - 2 vs 2. Choose 2 boosting fighters and 2 random. Do not enter any code at the loading screen. The trick/steps are the same as for boosting the 100 wins/150 X-ray attacks. The only thing you do is uppercuts now. You should spill ~1000 pints of blood per match.