It seems quite difficult to deal with the wizard in clash royale, but really very easy if you follow the tips below.
If you have Fireball (Fireball) and rival wizard placed behind the tower, just fire them bridge! Of course, you should make sure that your opponents do not have much more Elixir you. (Fun fact: as long as Fireball (Fireball) your level is higher than the Wizard, you can 1 hit kill it).
People often playing behind a tankker wizard like Giant or Golem, wait until they pass through your land then placed on top of a powerful hitter Wizard (Knight, Pekka, Prince, Dark Prince, ...) .
Swarm vs wizard
Barbarian can deal with the perfect wizard and also give you a perfect start. Do not place them too far Wizard if they die before the attack was to the Wizard. The perfect way to deal with the Wizard is to drop your Barbarians pack Wizard Wizard and can cause damage only 1 Barbarian.
barbarians vs wizard
If Wizard targeting your tower, do not put your troops behind the tower as Wizard damage widespread. The best option is to put your army behind them, or in the middle If you use long-range forces.