You don’t need anything under Attacks other than standard issue undercrackers (or chamois if you want), they’re shorts not overshorts. Not sure what Stoats means really- you might choose to wear something under but there’s no need at all
No water comes through mine… Though, I don’t like 3/4s so I wear the standard shorts and a bit of water does get up through the legholes as you’d expect.
All in all they’re extremely good- a little noisy when riding but otherwise I just treat them as regular shorts. Tough, too- I’ve torn mine slightly but they’ve been crashed in more times than I care to think about so one small tear is very good going.