here are some strats for cata xd
strat 1 (solo) - go 4 fighter 2 heal ( healer hg + adv rit glove) the rest is fighter and kite cata :D or you can go 4 tank 2 heal :D (use bless only and dodge a bit)
strat 2 (duo) - 1 person goes cleric ( 4 heal 2 war) and the other goes full mage , the cleric holds cata's threat , while the mage stays in a 3x3 box away from the cleric while shooting cata , or 1 person goes 2 mage 4 heal and the other goes 4 mage 2 heal , the mage takes threat , healer stans in a 3x3 box away or 2 mages (with adv rit) , 1 dodge healer while doing dps and the other static :P
strat 3 (3+ people) - 2 people goes full dps and a healer (same like duo)