Can a barabrian while affected by its 16th level feat "Dragon Transformation", use its class action like for example "Sudden Charge" (1st level)?
There is nothing preventing a polymorphed character from taking such an action that I can find.
If you take on a battle form with a polymorph spell, the special statistics can be adjusted only by circumstance bonuses, status bonuses, and penalties. Unless otherwise noted, the battle form prevents you from casting spells, speaking, and using most manipulate actions that require hands. (If there’s doubt about whether you can use an action, the GM decides.) Your gear is absorbed into you; the constant abilities of your gear still function, but you can’t activate any items.
A polymorph effect only prevents the character from casting spells, speaking and using most manipulate actions that require hands.
Since Sudden Charge is not a manipulate action that requires a hand, it is still viable.
Thanks!
The attack in Sudden Charge is a strike action, which is done with the natural attack of the Dragon. So its not as if you are using another attack, which would run into rules problems with the Dragon form spell.
AFAICT all of these type of feats work fine.