Hi! Randbats @ and sets discussions contributor here.- +1 speed allows you to outright win much more than outrage does.
- strong dragon stab is rarely a necessity. EQ hits everything really hard anyways, edge hits the flying types.
- chomp has great physical bulk so even at -1, it will survive almost all neutral physical hits
- I wouldn't call 90% accuracy "inaccurate". Lets just run rock slide instead of edge on everything then.
It doesnt need to replace outrage, but the sheer utility of +1 speed is undeniable, especially since chomp sits at a decent speed tier and will outspeed everything except the fastest scarfers. after an sd, SS will kill alot of neutral targets with slight chip, even if it gets lower hits and then ur a +2 attack +1 speed demon machine that either forces a dmax or wins on the spot. normal SD chomp gets outspeed by so much and ruins its potential as a breaker
I used to think Scale Shot was almost mandatory on Garchomp but truth is, it's not a good move at all in a format where Atk EVs aren't maxed out.
• You will find yourself struggling to get KOs in a lot of situations; for example, a +2 Scale Shot from Garchomp only has a slight chance to 2HKO Mew with 3 hits, where Outrage has a chance to OHKO after Stealth Rocks.
• Having a strong Dragon STAB is extremely good in Random Battles, simply because as opposed to a well-built team in a regular tier, Random Battle teams don't always have a Dragon resist, let alone an immunity. Switching into Garchomp will be much easier if the threat of being hit by a Dragon-type move doesn't exist because of Scale Shot pathetic's base power and shaky accuracy (I mean, 90% Acc for a 60ish BP move? yikes).
• The matter of Chomp living neutral physical moves at -1 is a good point... but that's just not a good argument at all. For example, a Choice Scarf Zapdos-Galar has a 23.4% chance to 2HKO regular Garchomp with either Brave Bird or Close Combat, while it always 2HKOs a -1 Garchomp (even if Chomp gets the -1 after Zapdos' first hit). Let's not forget that a +1 Chomp will be slower than a lot of Scarf users, including the aformentioned Zapdos-Galar.
• Going back to the accuracy thing, the debate of Stone Edge vs. Rock Slide is extremely different from the Scale Shot vs. Outrage. On one hand, you have a 100 BP move with 80% Acc, and a 75 BP move with 90% Acc; the drawback of having 10% less accuracy on Edge is outweighted by the much higher BP. In our case, you have a 90% Accurate move with a shaky BP because you're more often than not going to get 2 or 3 hits, vs a 120 BP 100 Acc move, so sure, 90% isn't inaccurate, but it makes the move even less reliable.
I hope you understand our point and this has been a debate for months really, but in the end Scale Shot is 100% worse than Outrage in this format. Have a nice day! :]