The short answer
Yes as a dictionary, no as a teacher. Pleco supports Traditional characters everywhere in the app, can show readings in Zhuyin instead of Pinyin, and — with one free add-on dictionary set as your default — shows Taiwan's pronunciations first in most cases. Two honest caveats: its stroke order diagrams follow mainland order, and Pleco is a reference tool, so it won't teach you to speak on its own.
Does Pleco support Traditional Chinese?
Yes, fully. Pleco's own App Store listing describes it as "PRC/HK/Taiwan-friendly" and says every part of the app supports both Traditional and Simplified characters. That covers search, definitions, handwriting lookup, the camera-based character recognition that lets you point your phone at a sign or menu, and flashcards. If you're reading in Taiwan, you won't be fighting the app to see the characters you actually encounter.
Does Pleco show Zhuyin?
Yes. According to Pleco's listing, headword readings can be shown in Zhuyin (Bopomofo) as well as Pinyin, so you can study with the phonetic system Taiwan's schools use rather than the mainland's. That's a genuine plus few dictionary apps match — if you're still learning the symbols themselves, our guide to learning Zhuyin starts from zero.
How do you get Taiwan pronunciations in Pleco?
Set the free Cross-Straits dictionary as your default. Many words are pronounced differently in Taiwan — a different tone, or no neutral tone where the mainland uses one — and out of the box, Pleco doesn't put those Taiwan readings first. On Pleco's own forum, its developer advises downloading the free Cross-Straits dictionary and dragging it to the top in Settings / Manage Dictionaries, which "should give you Taiwan pronunciation first in most cases." He has also said a separate, prioritized Taiwan pronunciation option is built into Pleco 4.0, in beta on iOS as of 2024, and that MOEDict — another add-on dictionary Pleco offers — carries only Taiwan pronunciations.