Perfect Cell was a fighter who often suppressed himself for sport, and only fought at his maximum capabilities (both pre and post zenkai) toward the very end the Cell arc. But I believe, he displayed 7 different battle powers (including suppressions) during his existence, and I'll explain every one.
1. Perfect Cell (initial suppression) - Right after Cell finishes transforming into his Perfect form, he lands. USSJ Vegeta is confident in himself that he can beat this Perfect Cell. Android 16 then tries to read Cell's battle power and says that Cell has drastically powered up, but Vegeta is still superior. Krillin also notes after getting kicked by Cell that Cell is masking his power and not to take the power Cell is putting out at the moment as a reference. So I think one thing is for certain
USSJ Vegeta > Perfect Cell (initial suppression)
To me, and this is my theory. Perfect Cell right here is suppressing himself to where he is only showing what Vegeta thought his new power would be. That being the combined power of his previous form (Semi Cell) and Android 18 who he just absorbed.
2. Perfect Cell ("warming up" suppression) - Cell almost immediately leaves his initial suppression and goes into his "warming up" suppression right before he takes on USSJ Vegeta. Now, he's not shown to actually display a power up, but the only way for him to be putting out less ki than USSJ Vegeta, to toying with him and tanking a kick to the neck means that he must have upped his ki significantly almost instantly before he started fighting USSJ Vegeta. After toying with Vegeta, Vegeta is mad and Cell tells Vegeta this is nothing and he's "only warming up". Anyways, in this suppressed state he's far superior to USSJ Vegeta, and USSJ Trunks. He defeats both USSJ Vegeta and USSJ 2 Trunks rather easily. This is also the level he later starts off fighting 50% MSSJ Goku at in the Cell games. He fights evenly with 50% MSSJ Goku and even after the 1st little spar with Goku, he tells Goku "that's enough of the warm ups". So to me, he's fighting here at the same level he displayed in his battle with USSJ Vegeta and USSJ 2 Trunks. Basically, his "warming up" suppression.
3. Perfect Cell ("warming up" suppression in pseudo USSJ 2 form) - After defeating USSJ 2 Trunks, Cell tells Trunks why the USSJ 2 transformation is inneffective even though USSJ 2 Trunks was putting out quite a bit more ki than Perfect Cell was in his "warming up" suppression. So, as a demonstration Cell goes into a pseudo USSJ 2 form and bulks up incredibly and his ki goes up, Trunks is stunned. More than likely here he is putting out more ki than USSJ 2 Trunks. However, Cell says that despite his ki being much higher because of this form, it's still way to slow and thus ineffective in battle. Cell then goes back to his normal state and out of this form.
4. Perfect Cell (powered up suppression) - In the Cell games, for a little while MSSJ Goku and Perfect Cell toy with one another. But when Cell tells MSSJ Goku to go full power Goku agrees and does. Cell was more than likely previously fighting in his warming up suppression (since nothing indicates otherwise), but as a response to Goku going full power, Cell does a massive power up in front of the Z senshi. Cell powers up to a level just a bit higher than that displayed by 100% MSSJ percent Goku more than likely because he's a good sport and admires Goku, and wants to have an exciting match. Cell and Goku battle for a while, but Cell eventually gains a decisive upper hand and Goku quits. Cell's ki has faded a bit and Goku gives Cell a senzu bean. Cell then recovers, but it's never noted by the z senshi that Cell's power has increased, only that it has been restored (they thought Cell was currently fighting at maximum power). Cell then takes on MSSJ Gohan. So Cell was fighting at the same level against MSSJ Gohan as he was against 100% MSSJ Goku, only Cell decides to actually "use his real speed" against Gohan. MSSJ Gohan get's kicked around for a while and Cell seems to have everything under control, but then Gohan get's angry, unleashes his true hidden power, and goes SSJ2. By this transformation Gohan has completely surpassed Cell.
5. Perfect Cell (full power) - Cell says he's going to show Gohan his "true terrifying power" and begins a massive power up. This power up has to be massive for 2 reasons. One, despite knowing he was getting toyed with by SSJ2 Gohan, Cell thinks he's going to kick Gohan's ass when he goes full power. Two, the Z senshi are amazed by the power up and act as if it's the greatest ki that they have ever sensed (more than likely they have not sensed SSJ2 Gohan's true power yet). Anyways, despite this massive power up, the full power Perfect Cell is still no match for SSJ2 Gohan to Cell's horrifying shock, and is staggered by just two punches.
6. Perfect Cell (full power in pseudo USSJ 2 form) - The full power Perfect Cell realizes he is no match for SSJ2 Gohan. Thus he get's infuriated and out of rage transforms into the pseudo USSJ 2 form and grows bulky and humongous. Trunks notes that although Cell has increased his power (ki), his speed has diminished and Cell has made the very same mistake he mocked Trunks for. This Cell proves to be no match for SSJ2 Gohan anyways, Gohan kicks him twice and Cell ends up regurgitating Android 18 and reverts back to his 2nd stage.
7. Perfect Cell (post zenkai aka "Super Perfect") - After self destructing because he realized he had no chance of winning. The biological core of Cell survives and he regenerates from the brink of death. Cell not only returns in his Perfect form, but also because he has a Saiyan genetic component he receives a large zenkai powering his Perfect form up incredibly. At his max, he now rivals SSJ2 kid Gohan in terms of power and his golden aura flashes with light blue electricity like a SSJ2.
This 'Super' Perfect Cell meets his end by the hands of SSJ2 kid Gohan in a massive Kamehameha struggle.
