Salamence out DPS palkia?

In terms of raw DPS, I'm assuming Salamence's lower bulk means it gains energy faster from attacks, allowing it to use Draco Meteor sooner.

Salamence's TDO is lower due to Draco Meteor being a single bar move compared to Rayquaza's Outrage being 2-bar. Single bar moves are generally less reliable than 2-bar counterparts, making the user more likely to faint with a partially filled bar. These cases also impact their DPS; compare that of a Rayquaza that gets to use one Outrage and that of a Salamence that faints before firing a single Draco Meteor.

Between Palkia and Salamence, the "winner" depends on what statistic you're looking at and at what level. Versus Latias, Palkia has a lower time to win than Salamence at L30. At L35, Salamence has a lower TTW. At L40, Palkia wins again. Interestingly, Palkia had a lower "estimator" number - rough number of trainers needed to win - in all cases, including where Salamence had a lower TTW. This is because of Palkia's bulk; fewer deaths means less time spent switching and reviving and more time attacking.

Considering that Salamence's and Palkia's attack stats are extremely close, some other factors that go into dps calculations come up.

Salamence's low defense / high HP spread allows it to gain energy at a slightly faster rate from enemy attacks than Palkia does w/ its higher def / lower HP spread, which results it in having a *miniscule* amount of extra DPS on average compared to Palkia (emphasis on miniscule). In practice their performance is very roughly the same, although at lower levels, Salamence is nearly OHKOed by Outrage and thus needs to be nearly maxed to reliably get Draco Meteors off.

The DPS spreadsheet provides a quick overview on what's good against X by a series of formulas, not actual simulations. The average relative error is around 2%. Simulators can reduce the error down further.
Further, you may tick the "Swap Discount" in the DPS spreadsheet to factor in the time of swapping, which puts Palkia ahead of Salamence.