Complex sentence: Squidward's new pure-bred snail Snellie is going to enter the great snail race, but even though Gary is a mutt, SpongeBob enters him, leading to disastrous consequences.
Split into simpler sentences: Squidward's new pure-bred snail, Snellie, is going to enter the Great Snail Race. Even though Gary is a mutt, SpongeBob enters him, leading to disastrous consequences.