an excellent question
- and one which comes up more often than we'd think.
There's been a few discussions over the years here and on the WotC forums (via the Wayback Machine),
I'm somewhat AFB with SWMinis at this time, so take my feedback with the appropriate quantity of salt hehe
(Hothie, Swinefeld, Sithborg, _NickName_, Boris, TheHutts, Kezzamachine, feel free to correct me here hehehe)
To your real question -
Yes, A follower who ends it's movement phase within 6 of Skywalker gains Momentum +4/+10 on it's applicable attacks,
it may make all its lawful/applicable attacks, either before or after moving (and any lawful combo of movement up to its speed, before or after attack)
and before you activate the next piece, a trooper or soldier may move only exactly an extra 2 squares at the end of its turn, or no extra squares.
(which might move the piece outside of 6 of skywalker's CE, and thus for that portion and resolution of effects, those pieces would lose momentum for anything which happens outside of the Skywalker CE range).
It would be this chain:
"Move pt 1 -> *within 6 of Skywalker, so +4/+10 against adj enemies if this character moved this turn. GMA allows the character to move and make all of its lawful attacks+extra attacks+twins etc...* -> Attack/s -> Move pt. 2 -> recurring resolve -> end of turn -> *Gree's CE comes into effect here, so +2 extra squares, if a stickler these must be exactly 2 full extra squares or no extra squares*."
So, lets look at some hypotheticals
maybe there is a piece which allows 1 trooper follower to make an attack at the end of its activation? or, when defeated, a non-unique follower may make an immediate attack. The "move 2 extra squares", might trigger the 'non-optional' Attack of Opportunity, which might defeat said hypothetical trooper... triggering a 'deathshot' or "avoid defeat" (which, if there is twin, is 2 deathshots...).
Yet - the trooper moved outside of the 6 square range of Skywalker, and so this 'deathshot' would not benefit from Skywalker's Momentum CE...
Or, Skywalker + Mouse Droid... a CE can be counted from the MouseDroid instead.
So, a Mouse droid is in the area, when the hypothetical trooper moves outside of 6 of skywalker, but is within 6 of a mouse droid...
Woe! The trooper twin deathshot is lawful, and momentum-y.
This is especially interesting for "Naboo Deathshot" style squads -
So, you can't as yet use that combo for a 'strafe attack lite' effect,
it cant move attack move attack etc... more than its lawful speed.
because the usual default is "Move -> Attack -> |recurring resolve|-> end of turn".
where order is important, and you cannot return to a previous step (ie, it's one-way).
Mobile attack and GMA change it somewhat to
"Move pt. 1 -> Attack -> Move pt 2 -> |resolve| -> end of turn"
rationale,
The operative word in Gree's CE is: "can", note the omission of the phrase/word "upto" - suggesting an exactly 2 square movement, or no squares. "extra' is not so much the operative, but, I can see how that might lead to confusion as to when this ability might come into effect
I believe, Gree triggers at end of turn (after the rest of an activation, before the next piece activates etc),
as opposed to end of round, or end of movement phase etc... so, it'd function like rolling cleave or surprise move/anticipation.
GMA applies, a character with Mobile attack may move before or after attacking,
a character with GMA may move and make all of its attacks, moving either before or after attacking.
I don't think Gree's CE allows a trooper to tack on an extra 2 squares to it's movement phase...
However, I have seen previous threads also wondering if that extra gree movement counts for Attack of Opportunity,
and the answer in that question was, yes... pieces which move due to Gree's CE were subject to Attacks of Opportunity, which resolved whenever the adjacency condition 'event-trigger' happened.
If, however,
people interpret Gree's CE to mean "Tack onto the movement of soldier or trooper type characters an extra 2 squares while moving",
I'd be interested to hear how that works.