This list was taken from Orders of Battle for the Red River Campaign, March - May 1864. I tried to whittle out the units which actually participated at Pleasant Hill on April 9, but most likely there are a few errors. Depending on which reference you use, there are a some differences in units that participated at Pleasant Hill, artillery units in particular. Using this as a start point, maybe some of the experts can tweak it to make it more accurate.

Orders of Battle for the Red River Campaign
Battle at Pleasant Hill, April 9, 1864

Confederate Forces
Maj. Gen. Richard Taylor commanding the District of Western Louisiana
Headquarters Escort Company (Louisiana Cavalry)—Capt. Joseph Benjamin
Unattached—2nd Battalion Louisiana Reserves

First Infantry Division
Maj. Gen. John G. Walker
First Brigade—Brig. Gen. Thomas N. Waul
12th Texas Infantry—Col. Overton C. Young
18th Texas Infantry—Col. Wilburn H. King
22nd Texas Infantry—Col. Richard B. Hubbard
13th Texas Cavalry, Dismounted—Col. Anderson F. Crawford
Second Brigade—Col. Horace Randal
11th Texas Infantry—Col. Oran M. Roberts
14th Texas Infantry—Col. Edward Clark
28th Texas Cavalry, Dismounted—Lt. Col. Eli H. Baxter Jr.
6th (Gould’s) Texas Cavalry Battalion—Lt. Col. Robert S. Gould
Third Brigade—Brig. Gen. William R. Scurry
16th Texas Infantry—Col. George Flournoy
17th Texas Infantry—Col. Robert T. P. Allen
19th Texas Infantry—Col. Richard Waterhouse Jr.
16th Texas Cavalry, Dismounted—Col. William Fitzhugh
First Division Artillery
Haldeman’s Texas Battery—Capt. Horace Haldeman
Gibson’s Battery
Daniel’s Texas Battery—Capt. James M. Daniel
Edgar’s Texas Battery—Capt. William Edgar

Second Infantry Division
Brig. Gen. Jean Jacque Alexandre Alfred Mouton (killed April , Brig. Gen. Camille Armand Jules Marie, Prince de Polignac
First Brigade—Col. Henry Gray
18th Louisiana Consolidated Infantry—Col. Leopold L. Armant (killed April , Lt. Col. Joseph Collins
28th Louisiana Infantry—Lt. Col. William Walker (killed April , Maj. Thomas W. Pool
Consolidated Crescent Regiment—(Louisiana) Regiment—Col. James Beard (killed April , Lt. Col. Abel W. Bosworth, Capt. William C. C. Claiborne, Jr.
Second Brigade—Brig. Gen. Camille J. Polignac, Col. James R. Taylor (killed April , Lt. Col. Robert D. Stone (killed April , Lt. Col. James E. Harrison
15th Texas Infantry—Lt. Col. James E. Harrison Maj. John W. Daniel
17th Texas Consolidated Cavalry, Dismounted—Col. James R. Taylor, Maj. Thomas F. Tucker
22nd Texas Cavalry, Dismounted—Lt. Col. Robert D. Stone, Maj. George W. Merrick
31st Texas Cavalry, Dismounted—Maj. Frederick J. Malone
34th Texas Cavalry, Dismounted—Lt. Col. John H. Caudle
Artillery—Maj. Thomas A. Faeries
Confederate Regular Battery, Capt. John T. M. Barnes
Bell (La.) Battery—Capt. Thomas O. Benton
St. Mary (La.) Cannoneers—Capt. Florian O. Cornay, Lt. John B. Tarleton.
Second Division Artillery—Maj. Joseph L. Brent
Reserve Battalion—Maj. Charles W. Squires
West’s Arkansas Battery—Capt. Henry C. West
Pelican (La.) Battery—Capt. B. Felix Winchester

Detachment, District of Arkansas
Brig. Gen. Thomas James Churchill
First Division
Brig. Gen. James C. Tappan
Tappan’s Brigade—Col. H. L. Grinstead
19th (Dawson’s) and 24th Arkansas Infantry—Lt. Col. William R. Hardy
27th and 38th Arkansas Infantry—Col. R G. Shaver
33rd Arkansas Infantry—Col. Hiram L. Grinstead
Etter’s Arkansas Battery—Capt. Chambers B. Etter
Gause’s Brigade—Col. Lucien C. Gause
26th Arkansas Infantry—Lt. Col. Iverson L. Brooks
32nd Arkansas Infantry—Lt. Col. William Hicks
36th Arkansas Infantry—Col. James M. Davie
[? 39th Arkansas Infantry—Col. James W. Rogan?]
Marshall’s Arkansas Battery—Capt. John G. Marshall

Second Division
Brig. Gen. Mosby M. Parsons
First Brigade—Brig. Gen. John B. Clark Jr.
8th Missouri Infantry—Col. Charles S. Mitchell
9th Missouri Infantry—Col. Richard H. Musser
Ruffner’s Missouri Battery—Capt. Samuel T. Ruffner
2nd Brigade—Col. Simon P. Burns
10th Missouri Infantry—Col. William M. Moore
11th Missouri Infantry—Lt. Col. Thomas H. Murray
12th Missouri Infantry—Col. Willis M. Ponder
16th Missouri Infantry—Lt. Col. Pleasant W. H. Cumming
9th Missouri Battalion Sharpshooters—Maj. Lebbeus A. Pindall
Lesueur’s Missouri Battery—Capt. Alex A. Lesueur

Cavalry Corps
Brig. Gen. Thomas Jefferson Green (killed April 12)

First Division
Brig. Gen. Hamilton P. Bee
Debray’s Brigade—Col. Xavier B. Debray
23rd Texas Cavalry—Col. Nicholas C. Gould (arrived April 9–10)
26th Texas Cavalry—Lt. Col. John J. Meyers
36th Texas Cavalry—Col. Peter C. Woods (arrived April 9–10)
Buchel’s Brigade—Col. Augustus C. Buchel (mortally wounded April 9)
1st Texas Cavalry—Lt. Col. William O. Yager
35th (Likens’) Texas Cavalry—Col. James B. Likens (arrived April 9–10)
Terrell’s Texas Cavalry—Col. Alexander W. Terrell

Second Division
Brig. Gen. James P. Major
Lane’s Brigade—Col. Walter P. Lane (wounded April , Col. George W. Baylor
1st Texas Partisan Rangers—Lt. Col. R. P. Crump
2nd Texas Partisan Rangers—Col. Isham Chisum
2nd Regt., Arizona Brigade—Lt. Col. John W. Mullen
3rd Regt., Arizona Brigade—Lt. Col. George T. Madison
Bagby’s Brigade—Col. Arthur P. Bagby
4th Texas Cavalry—Col. William P. Hardeman
5th Texas Cavalry—Maj. Hugh A. McPhaill
7th Texas Cavalry—Lt. Col. Philemon T. Herbert Jr. (mortally wounded April , Lt. Col. Gustave Hoffman
13th Texas Cavalry Battalion—Lt. Col. Edward Waller Jr.
Vincent’s Brigade—Col. William G. Vincent (operated independently)
2nd Louisiana Cavalry—Col. William G. Vincent
4th (7th) Louisiana Cavalry—Col. Louis Bush
Horse Artillery—Maj. Oliver J. Semmes
Grosse Tete (La.) Flying Artillery Battery—Capt. John A. A. West
Gibson’s Texas Battery—Capt. William E. Gibson (arrived about May 10)
McMahan’s Texas Artillery Battery—Capt. Martin Van Buren McMahan
Moseley’s Texas Artillery Battery—Capt. William G. Moseley
Valverde (Tex.) Artillery Battery—Capt. Thomas D. Nettles

Louisiana State Guard
1st Louisiana Battalion Cavalry—Lt. Col. Benjamin W. Clark
2nd Louisiana Battalion Cavalry—Lt. Col. Henry M. Favrot
Miscellaneous
Harrison’s Louisiana Cavalry Battalion—Lt. Col. William Harrison
Red River Scouts (La.) Cavalry Battalion (two companies)—Capt. Willis A. Stewart
1st Trans-Mississippi Cavalry Battalion—Maj. Thomason J. Bird
Crescent Artillery (Company A)—Capt. T. H. Hutton

Union Forces
Major General Nathaniel Prentiss Banks, Commander Department of the Gulf

13th Army Corps (Detachment)
Brig. Gen. Thomas E. G. Ransom

Third Division
Brig. Gen. Robert A. Cameron
First Brigade—Lt. Col. Aaron M. Flory
46th Indiana Infantry—Capt. William M. DeHart
29th Wisconsin Infantry—Maj. Bradford Hancock
Second Brigade—Col. William H. Raynor
24th Iowa Infantry—Maj. Edward Wright
28th Iowa Infantry—Col. John Connell
56th Ohio Infantry—Capt. Maschil Manring Artillery
1st Missouri Light Artillery, Battery A—Lt. Col. Elisha Cole
Ohio Light Artillery, 2nd Battery—Lt. William H. Harper

4th Division
Col. William J. Landram
First Brigade—Col. Frank Emerson
77th Illinois Infantry—Lt. Col. Lysander R. Webb
67th Indiana Infantry—Maj. Francis A. Sears
19th Kentucky Infantry—Lt. Col. John Cowan
23rd Wisconsin Infantry—Maj. Joseph E. Greene
Second Brigade—Col. Joseph W. Vance.
130th Illinois Infantry—Maj. John B. Reid
48th Ohio Infantry—Lt. Col. Joseph W. Lindsey
83rd Ohio Infantry—Lt. Col. William H. Baldwin
96th Ohio Infantry—Lt. Col. Albert H. Brown Artillery
Indiana Light Artillery, 1st Battery—Capt. Martin Klauss
Chicago Mercantile Battery—Lt. Pinkney S. Cone

19th Army Corps
Maj. Gen. William B. Franklin

First Division
Brig. Gen. William H. Emory
First Brigade—Brig. Gen. William Dwight
29th Maine Infantry—Col. George L. Beal
114th New York Infantry—Lt. Col. Henry B. Morse
116th New York Infantry—Col. George M. Love
153rd New York Infantry—Col. Edwin P. Davis
161st New York Infantry—Lt. Col. William B. Kinsey
Second Brigade—Brig. Gen. James W. McMillan
15th Maine Infantry—Col. Isaac Dyer
160th New York Infantry—Lt. Col. John B. Van Petten
47th Pennsylvania Infantry—Col. Tilghman H. Good
13th Maine Infantry—Col. Henry Rust Jr.
Third Brigade—Col. Lewis Benedict (killed April 9)
30th Maine Infantry—Col. Francis Fessenden
162nd New York Infantry—Lt. Col. Justus W. Blanchard
173rd New York Infantry—Col. Lewis M. Peck
165th New York Infantry—Lt. Col. Gouverneur Carr Artillery
1st Delaware Battery—Capt. Benjamin Nields
Battery L, 1st U.S. Artillery—Lt. Franck E. Taylor
1st Vermont Battery—Capt. George T. Hebard

Cavalry Division
Brig. Gen. Albert L. Lee
First Brigade—Col. Thomas J. Lucas
14th New York Cavalry—Maj. Abraham Bassford
16th Indiana Mounted Infantry—Lt. Col. James H. Redfield
2nd Louisiana Mounted Infantry—Maj. Alfred Hodsdon
Third Brigade—Col. Harai Robinson
1st Louisiana Cavalry (U.S.)—Maj. Algernon S. Badger
87th Illinois Mounted Infantry—Lt. Col. John M. Crebs
Fourth Brigade—Col. Nathan A. M. “Goldlace” Dudley
2nd Illinois Cavalry—Maj. Benjamin F. Marsh Jr.
3rd Massachusetts Cavalry (31st Massachusetts Mounted Infantry)—Lt. Col. Lorenzo D. Sargent
2nd New Hampshire Cavalry (8th New Hampshire Mounted Infantry)—Lt. Col. George A. Flanders
Fifth Brigade—Col. Oliver R Gooding
18th New York Cavalry, Companies K and D—Capt. William Davis
3rd Rhode Island Cavalry (detachment)—Maj. George R Davis
2nd New York Veteran Cavalry (?)—Col. Morgan H. Chrysler
Artillery
Rawles’s Battery (Battery G, 5th U.S. Light Artillery)—Lt. Jacob B. Rawles
6th Missouri Cavalry, Howitzer Battery—Capt. H. H. Rottakan
2nd Battery (B) Massachusetts Light Artillery—Capt. Ormand F. Nims

16th Army Corps, Army of the Tennessee
Brig. Gen. Andrew J. Smith

First Division
Second Brigade—Col. Lucius F. Hubbard
47th Illinois Infantry—Col. John D. McClure
5th Minnesota Infantry—Maj. John C. Becht
8th Wisconsin Infantry—Lt. Col. John W. Jefferson
Third Brigade—Col. Sylvester G. Hill
35th Iowa (nonveterans 8th and 12th Iowa attached)—Lt. Col. William B.Keeler
33rd Missouri (nonveterans, 11th Missouri attached)—Col. William H. Heath

Third Division
Brig. Gen. Joseph A. Mower
First Brigade—Col. William F. Lynch
58th Illinois Infantry—Maj. Thomas Newlan
119th Illinois Infantry—Col. Thomas J. Kinney
89th Indiana (nonveterans, 52nd Indiana attached)—Col. C. D. Murray
Second Brigade—Col. William T. Shaw
14th Iowa Infantry—Lt. Col. Newbold
27th Iowa Infantry—Col. James J. Gilbert
32nd Iowa Infantry—Col. John Scott
24th Missouri (nonveterans, 21st Missouri attached)—Maj. Robert W. Fyan
Third Brigade—Col. Risdon M. Moore
49th Illinois Infantry—Thomas W. Morgan
117th Illinois Infantry—Lt. Col. Jonathan Merriam
178th New York—Col. Edward Wehler
Artillery
3rd Indiana Battery—Capt. James M. Cockefair
9th Indiana Battery—Capt. George R. Brown

17th Corps
Detached to Brig. Gen. A. J. Smith (16th Corps)
Second (Provisional) Division
Brig. Gen. Thomas Kilby Smith
First Brigade—Col. Jonathan B. Moore
41st Illinois Infantry—Col. John M. Nale
3rd Iowa Infantry—Lt. Col. James Tullis
33rd Wisconsin Infantry—Maj. Horatio H. Virgin
Second Brigade—Col. Lyman M. Ward
81st Illinois Infantry—Lt. Col. Andrew W. Rogers
95th Illinois Infantry—Col. Thomas W. Humphrey
14th Wisconsin Infantry—Capt. Carlos M. G. Mansfield
Artillery
1st Missouri Light Artillery, Battery M—Lt. John M. Tiemeyer