Most players per team: Home Runs >= 50, 40, 30.

Through 2015 at least three players with at least 30 Home Runs (HR) on the same team has been done 55 times.

The first team with at least three players with at least 30 HR:

1929 Philadelphia Phillies

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Chuck Klein	43	1929	24	PHI	NL	149	679	616	126	219	45	6	145	54		61	0	9			5		.356	.407	.657	1.065	*98
2	Lefty O'Doul	32	1929	32	PHI	NL	154	732	638	152	254	35	6	122	76		19	4	13			2		.398	.465	.622	1.087	*79
3	Don Hurst	31	1929	23	PHI	NL	154	692	589	100	179	29	4	125	80		36	3	20			10		.304	.390	.525	.914	*3

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/24/2016.

Teams have had four players hit at least 30 HR nine times, most recently by the 2009 Phillies. The others:
Colorado: 1995, 1996, 1997, 1999
Atlanta: 1998,
Angels: 2000
Toronto: 2000
Cubs: 2004

Three teammate outfielders, 30 home runs each, same year: 1941 Yankees, 1963 Twins. Tuesday, September 20, 2016

Babe Ruth and Lou Gehrig were the first teammates to hit at least 40 HR in the same season and the only ones prior to the 1953 Brooklyn Dodgers (Duke Snider 42, Roy Campanella 41). Ruth and Gehrig did it in 1927 (60, 47), 1930, 1931. 1954 Dodgers: Gil Hodges 42, Snider 40.

Three teams have had three players hit at least 40 HR:

1973 Atlanta Braves

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Davey Johnson	43	1973	30	ATL	NL	157	651	559	84	151	25	0	99	81	9	93	9	0	2	8	5	3	.270	.370	.546	.916	*4/H
2	Darrell Evans	41	1973	26	ATL	NL	161	733	595	114	167	25	8	104	124	8	104	3	3	8	9	6	3	.281	.403	.556	.959	*53/H
3	Hank Aaron	40	1973	39	ATL	NL	120	465	392	84	118	12	1	96	68	13	51	1	0	4	7	1	1	.301	.402	.643	1.045	*79H

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/24/2016.

Those 1973 Atlanta Braves: was there something in the water? Tuesday, August 31, 2010

1996 Colorado Rockies

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Andres Galarraga	47	1996	35	COL	NL	159	691	626	119	190	39	3	150	40	3	157	17	0	8	6	18	8	.304	.357	.601	.958	*3/H5
2	Ellis Burks	40	1996	31	COL	NL	156	685	613	142	211	45	8	128	61	2	114	6	3	2	19	32	6	.344	.408	.639	1.047	*78/H
3	Vinny Castilla	40	1996	28	COL	NL	160	673	629	97	191	34	0	113	35	7	88	5	0	4	20	7	2	.304	.343	.548	.892	*5/H

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/24/2016.

1997 Colorado Rockies

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Larry Walker	49	1997	30	COL	NL	153	664	568	143	208	46	4	130	78	14	90	14	0	4	15	33	8	.366	.452	.720	1.172	*9/3H8D
2	Andres Galarraga	41	1997	36	COL	NL	154	674	600	120	191	31	3	140	54	2	141	17	0	3	16	15	8	.318	.389	.585	.974	*3/H
3	Vinny Castilla	40	1997	29	COL	NL	159	668	612	94	186	25	2	113	44	9	108	8	0	4	17	2	4	.304	.356	.547	.904	*5/H

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/24/2016.

And, of course, the one and only team with more than one player hitting at least 50 HR in the same year:

1961 New York Yankees

Rk	Player	HR	Year	Age	Tm	Lg	G	PA	AB	R	H	2B	3B	RBI	BB	IBB	SO	HBP	SH	SF	GDP	SB	CS	BA	OBP	SLG	OPS	Pos
1	Roger Maris	61	1961	26	NYY	AL	161	698	590	132	159	16	4	141	94	0	67	7	0	7	16	0	0	.269	.372	.620	.993	*98/H
2	Mickey Mantle	54	1961	29	NYY	AL	153	646	514	131	163	16	6	128	126	9	112	0	1	5	2	12	1	.317	.448	.687	1.135	*8/H

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 9/24/2016.

Mantle & Maris still only teammates to hit 50 HR. Tuesday, June 28, 2011

Mantle and Maris are still the only teammates to hit 50 HR. Not only are they the only pair to hit 50 in the same season but they are the only teammates to do it in any seasons.
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