Since I haven't actually seen it, I can't be sure, but my understanding of that 'season' is that it only has Optimus and a kid as 'bookends' to the actual adventures. Unless they talk about how he became a Powermaster in the cartoon universe, VS13 isn't going to get any answers from there. But I guess it is canonical, if he is actually referring to his adventures in the original cartoon, and is currently in the form of a Powermaster.
Since you are wanting to know about Powermaster Prime, the following has spoilers, but if you decide to want to find out about it yourself by acquiring all the comics, please skip past the rest of this posting.
Unfortunately, that is probably true by page/panel count, but the Original Optimus did appear in more issues than the PM Optimus, albeit by just 3 (and a couple more if you count the mini-series issues).
We had 80 'regular' issues of the US Marvel Comic, of which the original Optimus appeared in 24 issues (only featured heavily in 10 (of the 80!!!), but his head appeared in 7, and he had brief appearances in 7), while the PM Optimus appeared in 21 (featured in 16, with 5 brief appearances). For the record, issue 80 is drawn like Actionmaster Optimus, but didn't come into contact with Nucleon, so is a difficult one to classify (so it isn't included in the numbers above). It could still be a PM, because Hi-Q is still inside him, but then, the 3 issues Hi-Q was in after Prime's death in #75, could also count towards PM Prime's tally, as he claimed to be Optimus.
(I wasted a little time today with this, but it gave me a good excuse to browse through my TFs comics, so it's all good)
Issues with Original Optimus - 1, 2, 3, 4, 12, 14(5pages), 15(6pages), 16(5pages), 19, 21(3pages), 22(4pages), 24, 26(6pages of his corpse), 34(3pages - flashback story), 40 (virtual image), 48 (flashback story).
Issues with just Original Optimus as a head - 5, 6, 7, 8, 9, 10, 11.
Issues with Powermaster Prime - 42, 44(is now a PM, but drawn as original for some reason), 49, 50, 51(1page), 52(1page), 56, 57, 58, 59, 60, 62(2pages), 65(3pages), 69, 70, 71, 72, 73, 74, 75, 76(3pages).
Issues with the debatable version - 80.
Issues without Optimus at all - 13, 17, 18, 20, 23, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 41, 43, 45, 46, 47, 53, 54, 55, 61, 63, 64, 67, 68, 77, 78, 79.
The point of all that though, is that it highlights the lack of the central Hero character kids of Gen1 era wanted. We had 80 issues, and only 26 featured 'the great, iconic' Optimus Prime, with another 11 having brief cameo appearances, and 7 just showing his 'head on a bench'. That left 34 issues without Optimus Prime - almost half the entire comic run. More than half if you don't count the issues with just his head sitting on a bench.
It's no wonder the cartoon was more popular, because kids could see their hero Optimus in just about every episode, but in the Comic, he was hardly ever in it. If it wasn't for the UK Gen1 comic (reprinted the US comic, and had extra exclusive stories), the European fans (and us when it started shipping here *shortly* before Ops death) would have had the same lack of exposure to Optimus.
But going back to your original query - Powermaster Optimus - where does it fit in.
Well, from issue 1 to 4 we had the original Optimus running around, but then Shockwave decapitated him, and he didn't get his body back until issue 12. He was fine until issue 24 when he pretty much killed himself to preserve his code of honour, but a copy of something (assumed to be his mind/spark/soul/whatever) was made to a disk (retconned by fans as being reformatted by the matrix to be able to hold his entire personality on an 80s floppy disk.
The Autobots got a hold of the disk, and after a brief Autobot civil war, the disk was taken to Nebulos to create a new body for Optimus, because Nebulos had the technology and experiance following the creation of the Headmasters and Targetmasters.
Optimus was reborn as a Powermaster, because the fuel on Nebulos had been poisoned to keep Cybertronians away for good - the Nebulon partnered with each Cybertronian was the way around using the poisoned fuel.
Optimus and the other PMs left Nebulos, and he went on back to his usual job of fighting Decepticons and sacrificing himself in times of trouble. Problem was, when he later died, his Nebulon partner was bonded to such a molecular level, that he was able to be later 'rebuilt' by The Last Autobot, into Optimus Prime... to sacrifice himself another day (in the Gen2 comic).