Last year (and I think it's the same this year) there are 32 roster spots for each team. 20 position players, 12 pitchers, at least 3 of those are relievers (in practice, you'll note many more relievers than that are chosen, but not by me).
AL East
1. NYY 97
2. TB 92
3. Bos 87
4. Tor
5. Balt
AL Central
1. Minn 97
2. Cle 87
3. Chicago
4. KC
5. Det
AL West
1. Hou 98
2. Oak 84
3. LAA 82
4. Tex 81
5. Sea
NL East
1. Atlanta 90
2. Philly 85
3. Wash 82
4. NYM
5. Miami
NL Central
1. Chi 87
1. Mil 85
3. StL 824. Cin
5. Pit
NL West
1. LAD 100
2. Col 83
2. Ariz
3. SD
5. SF 68
AL All Star Team
Starters
C J.McCann CWS 2.6
1B C.Santana Cle 2.5
2B DJ LeMahieu NYY 3.95
SS M.Semien Oak 3.15
3B A.Bregman Hou 4.2
LF J.Gallo Tex 3.35
CF M.Trout LAA 5 MVP
RF M.Betts Bos 3.35
DH D.Vogelbach - Sea 2.2
SP M.Minor Tex - 4.9 Cy Young
Reserves
C R.Chirinos Hou 2.35
C G.Sanchez NYY 2.35
1B CJ Cron Min 2.05
2B B.Lowe TB 2.85
SS J.Polanco Min 3.05
SS X.Bogaerts Bos 2.65
3B M.Chapman Oak 3.25
OF B.Buxton Min 2.8
OF G.Springer Hou 2.9
OF M.Kepler Min 2.65
OF W.Merrifield KC 2.5
Pitchers
J.Verlander Hou 3.5
L.Giolito CWS 3.1
C.Morton TB 2.95
M.Boyd Det 2.8
J.Berrios Min 2.55
Relievers
L.Giolito CWS 3.1
C.Morton TB 2.95
M.Boyd Det 2.8
J.Odorizzi Min 2.7
J.Means Balt 2.65
M.Stroman Tor 2.65J.Means Balt 2.65
J.Berrios Min 2.55
Relievers
B.Workman Bos 1.95
B.Hand Cle 1.9
K.Giles Tor 1.75
B.Hand Cle 1.9
K.Giles Tor 1.75
NL All Star Team
Starters
C W.Contreras Chi 3
1B M.Muncy LAD 3.45
2B K.Marte Ari 3.6
SS P.DeJong StL 3.4
3B N.Arenado Col 3.05
LF J.McNeil NYM 2.45
CF R.Acuna Atl 3.25
RF C.Bellinger LAD 6.85 - MVP
DH C.Yelich Mil 4.4
SP M.Scherzer Wash 4.35-Cy Young
Reserves
C Y.Grandal Mil 2.6
1B P.Alonso NYM 3.2
1B F.Freeman Atl 2.75
1B J.Bell Pit 2.7
2B M.Moustakas Mil 2.95
SS J.Baez Chi 3.1
SS T.Story Col 3
3B A.Rendon Wash 2.9
OF B.Anderson Mia 1.95
OF A.Verdugo LAD 2.4
OF M.Conforto NYM 2.7
Pitchers
H.Ryu LAD 3.9
Z.Greinke Ari 3.8
J.DeGrom NYM 3.2
M.Soroka Atl 2.8
C.Hamels Chi 2.75
G.Marquez Col 2.65
L.Castillo Cin 2.65
Z.Eflin Phi 2.45
Relievers
J.Hader Mil 2.55
K.Yates SD 2.1
W.Smith SFG 1.75