Pretty much, yeah.
You take the IV at the top and read the column down to see the minimum level you need to hit to deal X amount of damage. A Machamp with 14a will reach its last offensive breakpoint for counter at level 33.5. One with 15a reaches this breakpoint a power-up early, saving you dust and candy. A Machamp with 2a would require maxing to do the same amount of damage.
Defense is the same way, but reverse. Machamp requires 15d to sustain the smallest amount of damage from both Metal Claw and Dragon Breath when maxed out. Any point or level lower and you're taking one more damage per hit.
There are different breakpoints with and without weather boost, as well as offensive ones for each stage of friendship. This means there are potentially 10 different levels where you can squeeze the most out of your Machamp - to keep it simple, pick the dropdown you'll experience the most and plan accordingly. If you'll always be raiding with best friends then look at the best friends breakpoints and power up as needed.
Charge moves also have breakpoints, but they're less important as fast move breakpoints for a variety of reasons. Firstly you use fewer charge attacks than you do fast attacks, so performance gains for reaching higher charged breakpoints are much smaller. Secondly, charge move strength (usually) increases pretty linearly - as long as you keep powering it up charge moves will get stronger. Third, it's way, way more expensive to reach those breakpoints than it is the fast move ones. As costs balloon while performance increases drop, it's not always advised to go beyond fast move breakpoints - Powering up a second machamp from L20 to L33.5 costs roughly the same as it does to max one out from L33.5, and you'll see much bigger gains in doing so.
Breakpoints help you find the lowest level you can get the most bang for your stardust buck. A 14a Machamp reaches its practical potential at level 33.5 because that's when Counter does the most damage. Powering up beyond that comes down to personal preference, as the cost/benefit ratio plummets.
EDIT: As an extra, Machamp will be supreme against Dialga according to Pokebattler. Breloom squeaks ahead against Thunder sets specifically, but Machamp will be your most reliable the other 2/3 of the time. Don't bring Groudon out unless it's clear weather.
