Will scout reveal their troops phalanx?
No! You will never know until you attack him or until he attacks you. You can get an idea based on his troop composition and the hero gear he is wearing and what heroes he is using but that doesn't guarantee anything.
If you researched level 10 intelligence report, you will see if he has prison 25 or not. If not, then no prison boost. If he has prison 25, then check if he has prisoners. If he does then he will surely have a prison boost.
Maxed Scouting reports will tell you-
Exact enemy troop composition
If their leader is out (where the biggest boost of power will be)
Any boosts they have running (attack, army size, and turf boosts)
Their buildings and levels. Level 25 infirms barracks and manors give troop boosts so useful
Reinforcements, garrison, shelter, and coalition troops. If the person is online you may wind up facing troops tagged as shelter and coalition should they decide to take the hit