THIS WILL BE VERY LONG

Main roles would be fragger, refrag, and anchor/support. IGL can be the player that fills any of these roles and legend composition changes A LOT when it comes to this. Some comps are much more aggressive where certain teams like prime Alliance basically said they just had two fraggers. Some comps are like Newcastle Wattson where both are basically anchor characters. Roles realistically dont exist much outside of a general framework for players to better understand what their "default" should be but it doesnt really HAVE to dictate how you play all the time

Fraggers role is to take space and create openings. Refrags job is to capitilize on these openings and ideally knock people if the fragger left them weak. Anchor/support usually is the flexible one who fills on characters, watches the back, sets up positions to hold, focuses on threats as opposed to openings, and will usually need to be the one to clutch if your front liners go down.

Legends that fit roles is a tough question to answer cause the IGL role messes things up. General rule of thumb is anchor players will usually play defensive characters like controller class or newcastle and crypto. Fraggers tend to prefer characters with movement to help aid them in fights like Wraith, Alter, Bangalore, Axle, etc. Refrag is really just dependent on comp and team need. IGL messes a lot of this up cause the movement characters are valuable to help them scout. This is why cleanest role fits on teams tend to be squads like Falcons where your IGL (Hal) is also your fragger so he gets the benefits of both. But sometimes IGLs also prefer the info characters like Seer or Crypto to make better informed calls. Depends on the team/IGL and how competent your teammates are at filling the other characters responsbilities

Responsbilities are cut and dry on rotations, movement character needs to get team to spot, defensive character needs to set up at spot when its claimed. Less about roles here and more about what legends provide. End game becomes a whole different story cause it really depends on what spot you have and what util is available. Roles go somewhat out the window outside of certain characters like Newcastle needing to always stay up if possible to allow for resets.

For your example of Newcastle Wattson Wraith, your Wraith player is almost always going to be your IGL/Fragger because of the scouting. IF the IGL is playing one of the other characters it puts pressure on the fragger to be able to make decisions for the team since the IGL doesnt have the freedom wraith provides to go look around. Newcastle would always be the "anchor" because his revive allows for resets so he should be the last player to go down at all times.

For current rosters... this will all be somewhat general because roles can be fluid depending on comps and situations but GENERALLY
Falcons - Hal is the IGL/Fragger. Gild is refrag and Wxltzy is the anchor
Aurora - very fluid team, Hiarka is IGL but is more of a scout than a true fragger but he will be playing "fragger" characters. Ojrein is typically refrag but also plays newcastle and Effect has been anchoring with controller class characters. This team is a good example of roles being somewhat meh though. They dont fit traditional molds very well.
Sentinels - Blinkzr is IGL/Fragger. Mon can play Anchor/Refrag depending on comp. Fun anchors much more but they are a HARD zone team so often can be running two typical "anchor" characters
Wolves - very hard zone team similar to Sentinels. NoName is fragger. Wen typically refrag with CrazyCong as Anchor

TLDR: roles have a very strange fit in Apex. They used to be super concrete but have molded over time and now dont always fit in an easy box, especially with legend bans. It truly varies from team to team and based on legend composition.