I don't think young dragons are supposed to have the lair actions or regional effects

They don't, They just used the standard green dragon description I think.

In the Adventure League, there’s an adventure called the Scroll Thief that featured a wyrmling dragon as a final boss with lair actions. It’s not unheard of to have smaller dragons with lair actions.

Some Dragons might excel above others and develop their lair sooner?, maybe it's hoard based?

When I threw my players, friends, into this battle it was seriously fun. I experienced this battle as a player and it took 3 hours.

After the lost mines of phindelver I DMed with my older brothers,  VenomFang the young green dragon from that campaign became an ally (mostly because of his infatuation with the female NPC of the group.). I've honestly loved how the character has sort of a bromance with one of my brother's (A human Fighter Noble).

THIS IS DND BASIC RULES!!!

Quote from cogema >>

I don't think young dragons are supposed to have the lair actions or regional effects

HE REFUSED BASIC DND RULES!!!

Lol

So whats the verdict, do YGD have lair actions? 

Everyone is concerned about if the young green dragon has Lair or not.  For me, from a DM story standpoint, it think it all comes down to how long the dragon has been setting up the place and if it really meets with the ultimate story of what you're going for and/or the intentions you have for the dragon.  Are they setting up a defensive post against adventurers or is the dragon making it easy for people to come to it so the dragon can make more minions with it's charming mind powers?  For the Mines of Phandelver quest, I would say it hasn't been there long enough to establish a real lair but if that's what floats your boat and you want to decimate the party and their morale, why not?  Do what you think works best for your narrative while keeping the party's "adventure attitude" in mind.  You want the party to at least find some shred of entertainment through your campaign, and all of it doesn't have to be positive.

Quote from PunkyDrewster81 >>

Everyone is concerned about if the young green dragon has Lair or not.  For me, from a DM story standpoint, it think it all comes down to how long the dragon has been setting up the place and if it really meets with the ultimate story of what you're going for and/or the intentions you have for the dragon.  Are they setting up a defensive post against adventurers or is the dragon making it easy for people to come to it so the dragon can make more minions with it's charming mind powers?  For the Mines of Phandelver quest, I would say it hasn't been there long enough to establish a real lair but if that's what floats your boat and you want to decimate the party and their morale, why not?  Do what you think works best for your narrative while keeping the party's "adventure attitude" in mind.  You want the party to at least find some shred of entertainment through your campaign, and all of it doesn't have to be positive.

 Agreed. When I run LMoP if the party fails to encounter or defeat Venomfang before they go through Wave Echo Cave they return to find Thundertree has been transformed into a lair with regional effects.

Quote from JazLynx >>

Quote from PunkyDrewster81 >>

Everyone is concerned about if the young green dragon has Lair or not.  For me, from a DM story standpoint, it think it all comes down to how long the dragon has been setting up the place and if it really meets with the ultimate story of what you're going for and/or the intentions you have for the dragon.  Are they setting up a defensive post against adventurers or is the dragon making it easy for people to come to it so the dragon can make more minions with it's charming mind powers?  For the Mines of Phandelver quest, I would say it hasn't been there long enough to establish a real lair but if that's what floats your boat and you want to decimate the party and their morale, why not?  Do what you think works best for your narrative while keeping the party's "adventure attitude" in mind.  You want the party to at least find some shred of entertainment through your campaign, and all of it doesn't have to be positive.

 Agreed. When I run LMoP if the party fails to encounter or defeat Venomfang before they go through Wave Echo Cave they return to find Thundertree has been transformed into a lair with regional effects.

 I’m not to that point yet and i’m in that campaign

Quote from PatrickDees >>

After the lost mines of phindelver I DMed with my older brothers,  VenomFang the young green dragon from that campaign became an ally (mostly because of his infatuation with the female NPC of the group.). I've honestly loved how the character has sort of a bromance with one of my brother's (A human Fighter Noble).

 
What?

Yes that seems unfair

That it gets to use lair actions

I have a question: It says on Intitiative count 20 (Losing initiative ties) that a green dragon can use a lair action. Even though I have the monster manual, I did not understand it. Can aomeone shed some light on this subject???

Quote from MiketheScourge >>

I have a question: It says on Intitiative count 20 (Losing initiative ties) that a green dragon can use a lair action. Even though I have the monster manual, I did not understand it. Can aomeone shed some light on this subject???

 Essentially the lair action has its own initiative, which is always 20. If anything else rolls a 20, it goes after that. 

Thanks😀😀😀 it helped a lot!!!