Add NUM_MON_PIC_FRAMES, and trainer pic size constants

include/constants/pokemon.h

@@ -260,6 +260,14 @@
 #define MON_PIC_HEIGHT 64
 #define MON_PIC_SIZE (MON_PIC_WIDTH * MON_PIC_HEIGHT / 2)
 
+// Most pokemon have 2 frames (a default and an alternate for their animation).
+// There are 4 exceptions:
+// - Castform has 4 frames, 1 for each form
+// - Deoxys has 2 frames, 1 for each form
+// - Spinda has 1 frame, presumably to avoid the work of animating its spots
+// - Unown has 1 frame, presumably to avoid the work of animating all 28 of its forms
+#define MAX_MON_PIC_FRAMES 4
+
 #define BATTLE_ALIVE_EXCEPT_ACTIVE  0
 #define BATTLE_ALIVE_ATK_SIDE       1
 #define BATTLE_ALIVE_DEF_SIDE       2