A few things:

-Inserted the sprites of Deoxys' form
-Fixed mistakes that I made while adding their cries and sprites
-Tweaked the Y coord of Deoxys' Defense Form's back sprite

graphics/pokemon/deoxys/normal_attack.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+64 40 32
+224 112 64
+160 80 56
+24 24 24
+128 192 192
+72 144 160
+152 112 144
+48 80 96
+96 64 112
+248 248 248
+192 192 208
+88 80 80
+120 120 112
+96 64 48
+168 88 56

graphics/pokemon/deoxys/normal_defense.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+64 40 32
+160 80 56
+224 112 64
+96 64 48
+240 176 144
+128 192 192
+72 144 160
+48 80 96
+152 112 144
+24 24 24
+248 248 248
+192 192 208
+96 64 112
+0 0 0
+0 0 0

graphics/pokemon/deoxys/normal_speed.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+48 80 96
+72 144 160
+128 192 192
+64 40 32
+224 112 64
+24 24 24
+160 80 56
+192 192 208
+152 112 144
+248 248 248
+96 64 112
+88 80 80
+120 120 112
+0 0 0
+0 0 0

graphics/pokemon/deoxys/shiny_attack.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+112 96 16
+248 232 64
+168 168 56
+24 24 24
+112 208 168
+72 160 112
+96 120 192
+56 96 88
+104 8 152
+248 248 248
+192 192 208
+80 80 80
+120 120 112
+96 64 48
+168 88 56

graphics/pokemon/deoxys/shiny_defense.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+112 96 16
+168 168 56
+248 232 64
+96 64 48
+248 248 216
+112 208 168
+72 160 112
+56 96 88
+96 120 192
+24 24 24
+248 248 248
+192 192 208
+104 8 152
+0 0 0
+0 0 0

graphics/pokemon/deoxys/shiny_speed.pal

@@ -0,0 +1,19 @@
+JASC-PAL
+0100
+16
+248 160 176
+56 96 88
+72 160 112
+112 208 168
+112 96 16
+248 232 64
+24 24 24
+168 168 56
+192 192 208
+96 120 192
+248 248 248
+104 8 152
+80 80 80
+120 120 112
+0 0 0
+0 0 0

sound/cry_tables.inc

@@ -910,9 +910,9 @@ gCryTable:: @ 869DCF4
 	cry_not Cry_Lycanroc_Dusk
 	cry_not Cry_Zygarde_10
 	cry_not Cry_Zygarde_Complete
-	cry Cry_DeoxysAttack
-	cry Cry_DeoxysDefense
-	cry Cry_DeoxysSpeed
+	cry Cry_Deoxys_Attack
+	cry Cry_Deoxys_Defense
+	cry Cry_Deoxys_Speed
 
 	.align 2
 gCryTable2:: @ 869EF24
@@ -1825,6 +1825,6 @@ gCryTable2:: @ 869EF24
 	cry2_not Cry_Lycanroc_Dusk
 	cry2_not Cry_Zygarde_10
 	cry2_not Cry_Zygarde_Complete
-	cry2 Cry_DeoxysAttack
-	cry2 Cry_DeoxysDefense
-	cry2 Cry_DeoxysSpeed
+	cry2 Cry_Deoxys_Attack
+	cry2 Cry_Deoxys_Defense
+	cry2 Cry_Deoxys_Speed

sound/direct_sound_data.inc

@@ -4015,15 +4015,15 @@ Cry_Zygarde_Complete::
 	.incbin "sound/direct_sound_samples/cries/cry_not_zygarde_complete.bin"
 
 	.align 2
-Deoxys_Attack::
+Cry_Deoxys_Attack::
 	.incbin "sound/direct_sound_samples/cries/cry_deoxys.bin"
 
 	.align 2
-Deoxys_Defense::
+Cry_Deoxys_Defense::
 	.incbin "sound/direct_sound_samples/cries/cry_deoxys.bin"
 
 	.align 2
-Deoxys_Speed::
+Cry_Deoxys_Speed::
 	.incbin "sound/direct_sound_samples/cries/cry_deoxys.bin"
 
 	.align 2

src/data/graphics/pokemon.h

@@ -3688,15 +3688,15 @@ const u32 gMonFrontPic_ZygardeComplete[] = INCBIN_U32("graphics/pokemon/zygarde/
 const u32 gMonBackPic_ZygardeComplete[] = INCBIN_U32("graphics/pokemon/zygarde/back_complete.4bpp.lz");
 const u32 gMonPalette_ZygardeComplete[] = INCBIN_U32("graphics/pokemon/zygarde/normal_complete.gbapal.lz");
 const u32 gMonShinyPalette_ZygardeComplete[] = INCBIN_U32("graphics/pokemon/zygarde/shiny_complete.gbapal.lz");
-const u32 gMonFrontPic_DeoxysAttack[] = INCBIN_U32("graphics/pokemon/deoxys/front_attack.4bpp.lz");
+const u32 gMonFrontPic_DeoxysAttack[] = INCBIN_U32("graphics/pokemon/deoxys/anim_front_attack.4bpp.lz");
 const u32 gMonBackPic_DeoxysAttack[] = INCBIN_U32("graphics/pokemon/deoxys/back_attack.4bpp.lz");
 const u32 gMonPalette_DeoxysAttack[] = INCBIN_U32("graphics/pokemon/deoxys/normal_attack.gbapal.lz");
 const u32 gMonShinyPalette_DeoxysAttack[] = INCBIN_U32("graphics/pokemon/deoxys/shiny_attack.gbapal.lz");
-const u32 gMonFrontPic_DeoxysDefense[] = INCBIN_U32("graphics/pokemon/deoxys/front_defense.4bpp.lz");
+const u32 gMonFrontPic_DeoxysDefense[] = INCBIN_U32("graphics/pokemon/deoxys/anim_front_defense.4bpp.lz");
 const u32 gMonBackPic_DeoxysDefense[] = INCBIN_U32("graphics/pokemon/deoxys/back_defense.4bpp.lz");
 const u32 gMonPalette_DeoxysDefense[] = INCBIN_U32("graphics/pokemon/deoxys/normal_defense.gbapal.lz");
 const u32 gMonShinyPalette_DeoxysDefense[] = INCBIN_U32("graphics/pokemon/deoxys/shiny_defense.gbapal.lz");
-const u32 gMonFrontPic_DeoxysSpeed[] = INCBIN_U32("graphics/pokemon/deoxys/front_speed.4bpp.lz");
+const u32 gMonFrontPic_DeoxysSpeed[] = INCBIN_U32("graphics/pokemon/deoxys/anim_front_speed.4bpp.lz");
 const u32 gMonBackPic_DeoxysSpeed[] = INCBIN_U32("graphics/pokemon/deoxys/back_speed.4bpp.lz");
 const u32 gMonPalette_DeoxysSpeed[] = INCBIN_U32("graphics/pokemon/deoxys/normal_speed.gbapal.lz");
 const u32 gMonShinyPalette_DeoxysSpeed[] = INCBIN_U32("graphics/pokemon/deoxys/shiny_speed.gbapal.lz");

src/data/pokemon_graphics/back_pic_coordinates.h

@@ -4632,7 +4632,7 @@ const struct MonCoords gMonBackPicCoords[] =
     [SPECIES_DEOXYS_DEFENSE] =
     {
         .size = 0x87,
-        .y_offset = 0x6
+        .y_offset = 0x9
     },
     [SPECIES_DEOXYS_SPEED] =
     {