Gohan (not trying): 30,000
Gohan (angry): 80,000
Gohan's Masenko: 100,000
Krillin: 25,000
Salt: 35,000
Mustard: 40,000
Mustard and Salt's shared beam: 75,000
At first Gohan is getting whacked around by Mustard and Salt but after they injure Krillin he gets angry and even their shared beam doesn't help and Gohan sends them both into the next dimension. Based on the Frieza saga levels, I assumed that both Gohan and Krillin's power levels raised by 5,000 over the year and their "fight" with their black water-misted friends meaning that both Mustard and Salt are stronger than Krillin and Gohan isn't at first but when he's angry he is. I figure Mustard and Salt's shared beam is their power levels combined (75,000) and Gohan was fine after it so his level was higher. Gohans Masenko was probably at 100,000 as it vaporised Mustard and Salt.
Gohan vs. Piccolo
Gohan: 32,000
Piccolo: probably around 50,000
Gohan fights Piccolo who is supposedly under the influence of the black water mist. Again Gohan doesn't really try and Piccolo probably went easy on Gohan and can't fight at his full power anyway because Kami is trapped in Garlic Juniors jar
Krillin vs Garlic Junior
Krillin: 30,000
Garlic Junior: 35,000
Krillin attempts to sneak the bottles containing Kami and Popo but is stopped by Garlic Junior. You may notice that later on Garlic Juniors power level is at 300,000 well thats because as the makyo star moves closer to the Earth Garlic Juniors level raises (before the Makyo his level was probably 900).
Gohan and Krillin vs. Spice and Vinegar (1st time)
Gohan (not angry): 32,000
Gohan's Masenko: 60,000
Krillin: 40,000
Spice: 45,000
Vinegar: 50,000
Gohan and Krillin take on Spice and Vinegar and again Gohan doesn't try at first and then does a Masenko which kills Vinegar and Spice but they are then revived with the light of the Makyo star. I bet your thinking whoah what a power increase for Krillin! but it makes sense when you think about it. Gohans Masenko verses Vinegar and Spice was probably not as strong as the one which kills Mustard and Salt as they were not vaporised and were revived.
Piccolo vs Garlic Junior
Piccolo: 400,000
Garlic Junior (not transformed): 300,000
Garlic Junior Transformed: 450,0000
Piccolo is easily able to take on Garlic Junior but when he transforms Piccolo has a problem as he cannot fight at full power bcause of Kami's weakness
Gohan and Krillin vs. Spice and Vinegar (2nd time)
Gohan (not angry): 50,000
Gohan's Masenko: 100,000
Krillin: 45,000
Spice (transformed): 70,000
Vinegar (transformed): 80,000
This time Gohan vaporises Vinegar and Spice. Gohan and Krillin probably gained a power boost after the first fight and Vinegar and Spice's power level proably grew as well with their transformation but this time Gohan's Masenko vaporises them both.
Piccolo vs. Garlic Junior (part 2)
Piccolo: 400,000
Piccolo Transformed: ranges between 450,000 and 400,000
Piccolo un-transformed: ranges between 200,000 and 300,000
Garlic Junior Transformed: 450,000
Piccolo transforms so he can match Garlic Juniors strength but un-transforms because of Kami's weakness and his power ranges because of this.
Gohan vs. Garlic Junior
Gohan: 60,000
Gohan's Masenko (kills Garlic Junior): 500,000
Gohan's Masenko (detroys Makyo star): about 1,000,000
Garlic Junior Transformed: 450,000
Garlic Junior untransformed: 900
In the final battle of the Garlic Junior saga Gohan takes on Piccolo and does a Masenko which kills Garlic Junior but thanks to his wish for immortality he is instantly revived so then Garlic Junior creates a new deadzone. Gohan protected Piccolo and Krillin with his shield but after they left Gohan fired at the Makyo star which after it was destroyed the explosion flung Garlic Junior back into the dead zone