Red Units:
Lyn 5* (Lv 28) - decent
Ike 5* (Lv 1) - excellent
Eliwood 4* (Lv 1)
Stalh 2* (Lv 3)
Alfonse 2* (Lv 20)
Hana 3* (Lv 11) - has life and death to give to a tome user
Sophia 2* (Lv 5)
Raigh 2* (Lv 1)
Blue Units:
Nephenee 5* (Lv 30) - good (edit thought she was a flier)
Effie 4* (Lv 25) - double check the IVs for Effie, make sure to level the one thats (+atk or +def or -spd) (can check her potential stats base 5* by going to the unlock potential screen with her)
Effie 4* (Lv 1)
Ninian 5* (Lv 25) - Essential for dance/sing
Jagen 4* (Lv 1) - one of the statistically worst units but has fortify cavalry to give
Nowi 4* (Lv 24) - Really good her lightning breath+ gives her distant counter for free.
Oboro 3* (Lv 1)
Sharena 2* (Lv 12) - pretty good worth promoting her to 4* or 5*
Green Units:
Gunter 4* (Lv 4) - has hone calvary buff to give
Narcian 4* (Lv 20) - emerald axe makes him at least usable against blue units
Barst 3* (Lv 1)
Frederick 3* (shoot, I thought he was 4*) (Lv 1)
Anna 2* (Lv 22) - probably the most well rounded hero of your current greens
Grey Units:
Brave Lyn 5* (Lv 32) - top tier obv
Maria 4* (Lv 25)
Wrys 4* (Lv 20) - all healers are kind of meh
Azama 4* (Lv 17)
Virion 2* (Lv 1) - sucks
Matthew 2* (Lv 1) - has hone speed 3 at 4* to feed to your core team
everything else is pretty much crap.