On April 16th, 2014, the South Korean ferry Sewol (세월호) carrying 476 people capsized and many people died in the accident.
On April 21st, 2014, TV Tokyo announced that they would be delaying the airing of XY24 - The Castle on the Seabed! Kuzumo and Dramidoro!! (海底の城！ クズモーとドラミドロ！！) as the episode featured Satoshi and friends diving underwater to look for the luxury ship "The Cussler" which was assumed to have sunk. Pokémon Get TV 28 did have a preview for XY24, though. XY25 - The Shoyo Gym Match! Pikachu VS Chigoras!! (ショウヨウジム戦！ピカチュウ対チゴラス！！) will air on April 24th, 2014 instead.
This is the message that TV Tokyo posted on the Official Pocket Monsters XY anime website: "Due to the current situation, the episode planned to be broadcast April 24th, "The Castle on the Seabed! Kuzumo and Dramidoro!!", has been temporarily put on hold. It is scheduled to be broadcast at a later date. Once an airdate has been decided, it will be announced on our website." (4/24に放送を予定していた『海底の城！クズモーとドラミドロ！！』は、都合により放送延期になりました。今後、改めて放送する予定です。日程は決ま り次第、HP上等で発表します。)
Source: http://www.tv-tokyo.co.jp/program/detail/22836_201404241900.html