diff --git a/play.pokemonshowdown.com/js/client-mainmenu.js b/play.pokemonshowdown.com/js/client-mainmenu.js
index 9655498a9d..08d9d05809 100644
--- a/play.pokemonshowdown.com/js/client-mainmenu.js
+++ b/play.pokemonshowdown.com/js/client-mainmenu.js
@@ -903,6 +903,9 @@
 			var bestOfDefault = format && BattleFormats[format] ? BattleFormats[format].bestOfDefault : false;
 			buf += '<p' + (!bestOfDefault ? ' class="hidden">' : '>');
 			buf += '<label class="checkbox"><input type="checkbox" name="bestof" /> <abbr title="Start a team-locked best-of-n series">Best-of-<input name="bestofvalue" type="number" min="3" max="9" step="2" value="3" style="width: 28px; vertical-align: initial;"></abbr></label></p>';
+			var teraPreviewDefault = format && BattleFormats[format] ? BattleFormats[format].teraPreviewDefault : false;
+			buf += '<p' + (!teraPreviewDefault ? ' class="hidden">' : '>');
+			buf += '<label class="checkbox"><input type="checkbox" name="terapreview" /> <abbr title="Start a battle with Tera Type Preview">Tera Type Preview</abbr></label></p>';
 			buf += '<p class="buttonbar"><button name="makeChallenge" class="button"><strong>Challenge</strong></button> <button type="button" name="dismissChallenge" class="button">Cancel</button></p></form>';
 			$challenge.html(buf);
 		},
@@ -955,6 +958,13 @@
 				format += 'Best of = ' + bestOfValue;
 			}
 
+			var teraPreview = $pmWindow.find('input[name=terapreview]').is(':checked');
+			if (teraPreview) {
+				var hasCustomRulesT = format.includes('@@@');
+				format += hasCustomRulesT ? ', ' : '@@@';
+				format += 'Tera Type Preview';
+			}
+
 			var team = null;
 			if (Storage.teams[teamIndex]) team = Storage.teams[teamIndex];
 
@@ -1404,6 +1414,18 @@
 					}
 				}
 
+				var $teraPreviewCheckbox = this.sourceEl.closest('form').find('input[name=terapreview]');
+				if ($teraPreviewCheckbox) {
+					var $parentTag = $teraPreviewCheckbox.parent().parent();
+					var teraPreviewDefault = BattleFormats[format] && BattleFormats[format].teraPreviewDefault;
+					if (teraPreviewDefault) {
+						$parentTag.removeClass('hidden');
+					} else {
+						$parentTag.addClass('hidden');
+						$teraPreviewCheckbox.prop('checked', false);
+					}
+				}
+
 				var $partnerLabels = $('label[name=partner]');
 				$partnerLabels.each(function (i, label) {
 					label.style.display = BattleFormats[format].partner ? '' : 'none';
diff --git a/play.pokemonshowdown.com/js/client.js b/play.pokemonshowdown.com/js/client.js
index 7b1ea5a67b..abd53ebf71 100644
--- a/play.pokemonshowdown.com/js/client.js
+++ b/play.pokemonshowdown.com/js/client.js
@@ -1341,6 +1341,7 @@ function toId() {
 					var tournamentShow = true;
 					var partner = false;
 					var bestOfDefault = false;
+					var teraPreviewDefault = false;
 					var team = null;
 					var teambuilderLevel = null;
 					var lastCommaIndex = name.lastIndexOf(',');
@@ -1354,6 +1355,7 @@ function toId() {
 						if (code & 16) teambuilderLevel = 50;
 						if (code & 32) partner = true;
 						if (code & 64) bestOfDefault = true;
+						if (code & 128) teraPreviewDefault = true;
 					} else {
 						// Backwards compatibility: late 0.9.0 -> 0.10.0
 						if (name.substr(name.length - 2) === ',#') { // preset teams
@@ -1418,6 +1420,7 @@ function toId() {
 						challengeShow: challengeShow,
 						tournamentShow: tournamentShow,
 						bestOfDefault: bestOfDefault,
+						teraPreviewDefault: teraPreviewDefault,
 						rated: searchShow && id.substr(4, 7) !== 'unrated',
 						teambuilderLevel: teambuilderLevel,
 						partner: partner,