Anyone know what formation he mainley used at molde
He's played mostly in 4231, but not dogmatic about it. Depending on personell he has also deployed 433 or 442, at times also with a back three although that does not seem to be his preference. Attacking full backs keep the width, while the the wide men in the attacking midfield band is more "inside forwards" (to use FM language). Lately he has been having a strong powerful striker on top (the son of Alfie Haaland), with a creative player behind him in front of the midfield. He has used a very young team here in Norway.
His playing style is more suited to top team than relegation battlers. I think one of the problems with the unsucessful spell in Cardiff was trying to play as he did back in Molde where he could dominate games in a way Cardiff never were capable of. A sometimes overly ambitious style. He has done som beatuiful attacking football when things have aligned in Molde, both possession based and through quick transitions. At one point our most dangerous attacking weapon was our right back, and goal/assits comes from a variety of sources. It remains of course to be seen if he can replicate this in the much more tactically developed premier league.
He has an attacking intent. Molde scored the most goals (by a big margin) in Norway this season. But we had equally more goal against as well, compared to the team that won the league (molde came 2nd). From what I have seen a weakness would be the amount of space left behind, and that sometimes leads to trouble. You'll need defensive players who are good at covering ground and speed would come in handy.
He has done fair enough in European football against teams that are better than Molde, som totally naive he might not be. Maybe he learnt something about that at Cardiff...