I agree with most of the stuff being said here, however i have a little issue. Many people talk about Below or Above Average PS while wanting Attack similar to that of Ferrothorn. This means that the CAP will have base 80 Speed at most, which is something i don't really like. If we are slower than Latios then it has the option to 2HKO us with HP Fire in sun, with LO or Specs, no matter how good special bulk we have. The only way to avoid the 2HKO from HP Fire would be to have Amazing ST and not low tier Amazing. However, if the CAP has a better Speed stat than Latios it can take the first hit and then at least weaken or OHKO back, or just heal. We can give to the CAP enough bulk to take one Specs DM or Specs HP Fire after SR with only max HP (we will need to max Speed too) but we cannot give to the CAP enough bulk to take two HP Fire in sun without Blissey-like special bulk, creating an opening for Latios to take out the CAP before it even does something.
A good Speed stat would be very useful for the CAP, as sun teams are offensive by nature and appreciate fast pivots much more than slow ones. As Deck Knight said, speed is bulk, as the CAP will more often than not get to move first, lessening the need for huge special bulk, and as i said again fitting better in sun teams in general. And there shouldn't be any worry of making the CAP too offensive or whatever, as with mediocre Attack and bad coverage (which most of the community favors i think), as well as weakness to common priority (Ice Shard and Mach Punch) the CAP will be just fine.
Now let's convert all this talk to something more specific:
Physical Tankiness (PT)
85 < PT < 115. I agree with everyone on this one. The boundaries i gave are to prevent the CAP from walling random physicall attackers (Scarf Terrakion for example) and to allow it to at least switch-into resisted STAB physical moves without losing too much health.
Special Tankiness (ST)
190 < ST < 210. This reflects what i said before about Speed. With more Speed than Latios we don't need enough bulk to survive two of its moves, and the same goes for Politoed. The ST i chose allows the CAP to take once any move from Latios and Politoed with only max HP investment, while healing or attacking first in the next turn.
Physical Sweepiness (PS)
170 < PS < 190. This looks different from what everybody else thinks but i already explained why. The PS is so big because the Speed is going to be big, not the Attack. The CAP should have just enough power to 2HKO max HP Latias uninvested imo, which means a ~100 Atk stat, which is a reasonable Attack stat for an utility role.
Special Sweepiness (SS)
70 < SS < 90. Once again, this looks different from the other suggestions, but Speed is the reason. The CAP should have awful SpA (40-50 in terms of base stats) and great Speed, which produce the SS i mentioned.
Finally, i agree that the BSR should be in these boundaries: 315 < BSR < 335.
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