I like the way this team turned out to be, thanks for all the time you put in this CCAT Pocket!
Anyways, if you've been having a lot of problems with stall, there might be a small change that can help against stall. Using Refresh on Latias instead of Reflect lets you 6-0 almost singlehandedly. After you sac every other team member so Latias can't be phazed out, Latias can set up on almost anything commonly found on stall teams. Thanks to Reflect protecting it from Toxic and Calm Mind + Recover protecting it from Ice Beam / Seismic Toss, Chansey and Blissey are easy setup fodder. Losing to Tyranitar and Scizor sucks, but that is what team members are for. Bulk Up Breloom already deals with Volt-Turn all by itself as well. Regardless, after you set up six Calm Minds almost nothing on stall can stop it. Curse Quagsire can take it on, but it provides a free switchin for Breloom or Gyarados. Jirachi can take on +6 Latias with luck on its side, but if you predict a Jirachi switchin you can switch right to Nidoking and launch an attack. All other Pokemon who can take a +6 Dragon Pulse don't have reliable recovery, so you can beat them quite easily (for example, see Heatran). Beware of stall teams with Choice Band Tyranitar though, that's another hard counter.
Another option you might want to try is changing around Gyarados's set. I think you're better off changing Latias's set, but it's purely preference so a change in Gyarados's set is worth a shot as well. However, this does open you up a little to Haxorus. The set shrang provided is a good option, but there's another Gyarados set that's pretty cool, namely the following set:
Gyarados @ Leftovers | Intimidate
Impish | 248 HP / 252 Def / 8 SpD
Dragon Dance / Waterfall / Rest / Sleep Talk
CroGyara does a good job at beating stall without Electric-type attacks. If you sac everything on your team, it can't be phazed out and safely set up unless the opponent has a Rotom-W, Gastrodon, Hidden Power Electric Vaporeon or Thunderbolt Starmie. Unfortunately, this is usually easier for stall teams to take on than the aforementioned Refresh Latias. Another thing you could try with this set is using Dragon Tail instead of Sleep Talk, as for one it allows you to phaze, but also allows you to hit Water-type immunes such as Gastrodon.
Anyways, if you've been having a lot of problems with stall, there might be a small change that can help against stall. Using Refresh on Latias instead of Reflect lets you 6-0 almost singlehandedly. After you sac every other team member so Latias can't be phazed out, Latias can set up on almost anything commonly found on stall teams. Thanks to Reflect protecting it from Toxic and Calm Mind + Recover protecting it from Ice Beam / Seismic Toss, Chansey and Blissey are easy setup fodder. Losing to Tyranitar and Scizor sucks, but that is what team members are for. Bulk Up Breloom already deals with Volt-Turn all by itself as well. Regardless, after you set up six Calm Minds almost nothing on stall can stop it. Curse Quagsire can take it on, but it provides a free switchin for Breloom or Gyarados. Jirachi can take on +6 Latias with luck on its side, but if you predict a Jirachi switchin you can switch right to Nidoking and launch an attack. All other Pokemon who can take a +6 Dragon Pulse don't have reliable recovery, so you can beat them quite easily (for example, see Heatran). Beware of stall teams with Choice Band Tyranitar though, that's another hard counter.
Another option you might want to try is changing around Gyarados's set. I think you're better off changing Latias's set, but it's purely preference so a change in Gyarados's set is worth a shot as well. However, this does open you up a little to Haxorus. The set shrang provided is a good option, but there's another Gyarados set that's pretty cool, namely the following set:
Impish | 248 HP / 252 Def / 8 SpD
Dragon Dance / Waterfall / Rest / Sleep Talk
CroGyara does a good job at beating stall without Electric-type attacks. If you sac everything on your team, it can't be phazed out and safely set up unless the opponent has a Rotom-W, Gastrodon, Hidden Power Electric Vaporeon or Thunderbolt Starmie. Unfortunately, this is usually easier for stall teams to take on than the aforementioned Refresh Latias. Another thing you could try with this set is using Dragon Tail instead of Sleep Talk, as for one it allows you to phaze, but also allows you to hit Water-type immunes such as Gastrodon.