What was the characteristics of the Greek dialects that were once spoken in western Anatolia?

I assume OP is asking about the West Anatolian dialects of Modern Greek, not Ancient Greek.

1. Not studied enough.

2. Not old. Pontic and Cappadocian are relic dialects, cut off from the rest of Greek for a millenium, and they are both archaic in phonology and morphology, and influenced by Turkish to a great extent. (Syntax in Pontic, which also picked up animacy from Caucasian languages; much more influence in Cappadocian, ranging even to vowel harmony.)

Western Anatolian dialects OTOH look a lot like mainstream Greek, and we know that Western Anatolian was islamised quickly; we assume they were resettled from Greece from the 16th century on.

3. Bithynian (NW Anatolia), from memory, is like Thracian (which I’m not counting as West Anatolian), though we know some Bithynian villages were settled from Epirus.

4. There were two villages on the Sea of Marmara settled from Tsakonia, though their Tsakonian was influenced by Thracian/Bithynian. Where are the Tsakonian villages in Turkey?

5. The dialect of Halicarnassus/Bordum (SW Anatolia) is pretty close to the Dodecanese.

6. The dialect of Smyrna/Izmir and its hinterland is not well studied at all, but seems to have been close to the Cyclades.

7. The only West Anatolian dialect that seems to have been old, and a relic from earlier times, was that of Livisi (Kayakoy village near Fethiye). It’s like Dodecanesian and Cypriot, but odd.

8. If Konya counts as Western Anatolia, then you can count the dialect of Silli as an old dialect as well; it’s a bit like Cappadocian.