Ignore the naysayers. Caldari do just fine in PvP - in fact, one of the most commpnly flown PvP ships in the game is the Drake.
The only reason people say otherwise is that the other three races - so, better than 3/4 of the ships flown in PvP - are armour tanked so it's easier to fit a minnie, Amarr or Gallente ship and still expect to be remote repped.
In practice, a well-fitted Caldari ship has more effective hit points and a comparable DPS to its peers, with the added advantage of damage type flexibility.
You specified Caldari battleships in your OP. the Raven is one of the most widely-flown ships in the game, and has long been a favourite of some very respected PvP corps. Most notably, Burn Eden are well known for preferring it over any other ship. The Scorp is an excellent ECM platform with decent damage output, and the Rokh, when fitted with blasters and a HP tank, is perfect for front line combat.
Let's focus on the Raven. a well-fit, well skilled Raven pilot can put out about 1200 to 1300 DPS. The mistake people keep making with PvP ravens is fitting shield boosters on them. Don't - use large shield extenders and give it lots of HP. minimise the cap usage in all areas aside from hardeners, and you'll have enough to run some remote reppers in those remaining two highslots. That combination makes the Raven a hard-hitter, fairly tough, and a welcome bit of logistics support all in one package.
Bear in mind that just because it's not outstanding in any one narrow field doesn't make it bad. The Raven's a versatile workhorse and well worth flying.
One thing I will say - Caldari ships rarely do well in solo PvP. but this is a MULTIPLAYER game - get some friends, spec in Caldari, show the narrow-minded idiots who think that PvP begins and ends with how personally l33t they and their ship are how wrong they are.