This is one of the better teams of BW2- can matchup well against almost anything so good job with that.
Changing Latias to max speed Timid is absolutely vital for Terrakion / Keldeo / Thund-T / Lando etc., I always thought you were running that already.
For Hippo I prefer 252 HP / 4 def / 252 SpD Impish because it's then excellent on both sides and you won't have to switch out of Hydreigon (Specs Draco doesn't OHKO), counter Sub Hydreigon, switch into Volc if you need to etc. You could try this new trend of making it full SpD Careful and wasting it's IVs so Genesect doesn't get a special attack boost but I'd rather not suck it's dick like that to deal with it.
If you're worried about Luke you could use an attacking Lando-T over Mamo- something like EQ / Stone Edge / HP Ice / U-Turn could go right on. You'll have to deal with Hippo getting Toxic'ed by Sub Glisc but that's all it can do and you won't be seeing a ton of them anyway.