Alexander does a Shadow Duel with Beze and Bence and takes their souls along with Obelisk the Tormentor. He then faces Tamas underestimating his skills, saying that he doesn't have any idea on how Tamas could get Slifer. They then start a Shadow Duel, which Alexander loses. After his loss, Alexander gives Tamas the remaining two God Cards in order for Darkness, the Master of Shadows to control Tamas himself.
Alexander then attends the new tournament and defeats a Shadow Duelist in the Top 8 with Shooting Quasar Dragon.
Arriving at the Top 4, he duels the possessed Tamas, underestimating him once again because of Shooting Quasar Dragon and gets defeated once again. After the Master of Shadows loses, Alexander takes his duel energy and the three God Cards, and claims that it's time for a new leader to guide the Shadow Duelists.
He then faces Tamas, winning by stealing Tamas' Dragon Master Knight. He then takes Tamas' soul and his Blue-Eyes White Dragons. After Tamas gets brought back from the Shadow Realm they do the final Shadow Duel, which Alexander loses because of Blue-Eyes Shining Dragon.
Alexander confronts Tamas and his friends in the beginning stages of the new tournament. While everyone else has their decks shifted around thanks to the unknown master of the tournament, Alexander is given Tamas's Blue-Eyes deck. He uses it against Obis, who is forced to use Beze's Black Luster Soldier deck, and defeats him easily.
When Tamas duels Kiber, Alexander gleefully tells Bence and Beze that he brought a useless deck filled with low-level monsters, apparently having prior knowledge of the randomization of the decks in this leg of the tournament. However, he is shocked just as they are when Tamas is once again possessed by Alexander's old master, Darkness.
Alexander duels againts Bence in the TOP 4, but he is eventually defeated and has to return the Blue-eyes Deck he got from Tamás.
Special Episode (2016)
Alexander stole Tamas' old Egyptian God Cards deck and challenge him into a duel. He manage to summon Obelisk The Tormentor, Slifer The Sky Dragon and The Winged Dragon of Ra. Until they were destroyed by Tamas' newly Beelze of the Diabolic Dragons. Alexander summoned Tamas' Blue-Eyes Shining Dragon until destroyed too. He used Soul Exchange to tribue Beelze to set Lightpulsar Dragon. Alexander summoned Dragon Master Knight (Tamas' most powerful monster) until it was destroyed by Tamas' Blue-Eyes with the effect of Honest not before Alexander activate Nutrient Z. Alexander later was defeated by Tamas' reborn Beelze of the Diabolic Dragons and forced to attack with Staunch Defender.
Season Four: Link Wars
Within the Shadow Realm, shortly after Darkness declares war upon the mortal world, he sends Alexander and a team of other Shadow Duelists to reclaim the God Cards from their current guardian, Schmirko . He assigns one of his other minions to be the Gatekeeper, a Sacred Beast duelist, just in case Alexander fails in his task.
Alexander and his team of Shadow Duelists defeat Beze 's men. He sends them ahead to the other side of the portal to weaken Schmirko. Before he himself can pass through the portal, Beze intercepts him and challenges him. Alexander accepts Beze's challenge, claiming to be a master in the "Extra Link".
They duel in the Shadow Realm, where the loser must remain forever. Alexander duels Beze using various monsters from the Danger! theme, World Gears, Phantom Knights and Knightmares. Beze counters with his Warrior-themed deck including Black Luster Soldier. Alexander eventually forms an Extra Link that renders all but World Gears monsters invulnerable, but Beze breaks the Extra Link with Black Luster Soldier - Envoy of the Beginning's removal effect, along with the trap card Rivalry of Warlords. Alexander then recovers and fusion summons Starving Venom Fusion Dragon, but Beze responds by summoning Buster Blader the Dragon Destroyer Swordsman and wins the duel.
Presumably with all other Shadow Duelists including the ex-Shadow Duelist Obis , Alexander remains trapped in the Shadow Realm.
Revenge of the Sacred Beasts
After his loss against Bézé and the destruction of his former master Darkness, Alexander thought about his past life. Therefore he came to the conclusion to finally leave his existence as Shadow Duelist behind and join the good side for the rest of his life. But since he isn't able to escape from the Shadow Realm, he decides to protect the gate which allows other creatures to enter and leave the realm.
One month after the events of Link Wars, Armityle (brother of Darkness) in the body of Obis arrives at the gate. Alexander realizes fast that Obis is not in control of his body and forbids Armityle to leave into the real world. This way, Armityle challenges Alexander to a Shadow Duel to get past him. During the last month, Alexander combined his own deck with the one of his death master and now confronts Armityle with both Danger monsters and Thunder Dragons. The duel becomes intense, but at the end Alexander wasn't strong enough anymore to handle the new power of the 3 Sacred Beasts. As he loses, he tells Armityle that there aren't any shadow duelists only for the Amrityle replied to Alexander that his brother, Darkness was weak just like his plans. Before Armityle departs. Alexander told him that Tamás and Bence will stop his evil plans for sure. After that he is left behind in the Shadow Realm, unable to escape.
Yu-Gi-Oh! Hngry VII [Heritage chapter]
Alexander shortly appears in episode 11 of the Heritage series. There he cooperated with currently unknown evil people who threaten the dimensions. Alexander promises that no one in his own dimension will get knowledge about this.
However, at this time of TMS, Alexander is the one, who posseses Shooting Quasar Dragon, and wears completely different clothes. And since in Heritage, there is only one copy of this card through dimensions, and other continuity errors, we can come to the conclusin, that this is most likely an alternate version of the Alexander from The Movie Series.
Alexander plays various Decks in the series, all of them being Swarm Decks. The first one is a TenguSynchro Deck, made most by monsters that can be Special Summoned or that Special Summon other monsters.