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Lyra Forest
Enter Lyra Forest like you did before but breifly pause as Professor Hastings explains how the Grass Poké Assist works. The Poison and Ground Poké Assists work in the same way, so listen carefully. Continue up a little further and stop again as Hastings explains the Water Poké Assist. This time listen even more carefully as the Rock and Bug Poké Assists work in the same way. Now you will come to some bundled hay. Capture a Torchic and use its Field Move to burn down the hay and then proceed onwards. Follow the path (capturing the Pichu if you want to heal up) until you reach a log. Double back and capture a Combusken after it jumps out of a bush. Now continue to Krokka tunnel.
Krokka Tunnel
Continue on, capturing a Rhydon to clear the mission.