Teambuilder: Fix bugs in form selection

Author: Marty-D

play.pokemonshowdown.com/js/client-teambuilder.js

@@ -3709,8 +3709,8 @@
 
 			var gen = Math.max(this.room.curTeam.gen, species.gen);
 			var dir = gen > 5 ? 'dex' : 'gen' + gen;
-			if (Dex.prefs('nopastgens')) gen = 'dex';
-			if (Dex.prefs('bwgfx') && dir === 'dex') gen = 'gen5';
+			if (Dex.prefs('nopastgens')) dir = 'dex';
+			if ((Dex.prefs('bwgfx') && dir === 'dex') || species.gen >= 8) dir = 'gen5';
 			spriteDir += dir;
 			if (dir === 'dex') {
 				spriteSize = 120;