My Sicizor isn’t gaining EXP

When I had my Syther it leveled up fine but once I leved it up to Scizor it stopped gaine EXP from battles.
Is there a to fix this???

 

Since Scizor is a generation two Pokemon, it won't gain experience in generation one unless it was received from an egg or you are trainer level 50, and since scyther is a generation one Pokemon, it gained experience in that region like normally. You will need to reach the second region to level up your scizor, good luck!