The clues that are useful in reconstructing Pangea include:
Fossils found by scientist. Fossils of the same plant and animal species on some of the continents that the oceans separate.
Matching folded mountains
If the continents were joined back. we would notice how the mountains match since they share for instance the same sample of rocks.
Glacial Deposits
Some places have glacial deposits but their temperatures are not cold to have glaciers.
Edge of Continents
Some continents such as South America and Africa fit each other if joined together like.