The vivid and colorful illustrations depicting the hot summer scenes usually do the trick. Also, an engaging plot with interesting characters can make it stand out.
Another story might be that during summer, Ben goes camping with his family. At the campsite, strange things start to happen, like the appearance of a mysterious glowing light in the forest. Ben, of course, uses his powers to investigate. He finds out that it's an alien device that has crashed there and he has to figure out how to deal with it before it causes any harm.
Ben 10 has many adventures in summer. For example, he might go on a road trip with his grandpa and Gwen. Along the way, they encounter various challenges that require Ben to use his alien powers. Maybe they come across a blocked road due to a landslide caused by an alien experiment gone wrong, and Ben has to transform into an alien with super strength to clear the way.
Ben Tennyson is obviously one of the main characters. His friends like Gwen and Kevin often appear as well. They usually accompany Ben on his summer adventures. Sometimes Grandpa Max also makes an appearance to offer guidance or help out when things get tough.
One interesting plot could be Ben exploring a new alien world during his summer vacation. He discovers a rare alien species and has to use his Omnitrix to protect them from a villain who wants to capture and sell them. Another plot might involve Ben and his friends going on a beach vacation, but they end up having to deal with an underwater menace using their combined skills.
To develop Summer better, give her a unique quirk like she always carries a special type of Pokemon treat that can calm any wild Pokemon. For Ben, you could show his backstory more, like how he became interested in being a Pokemon Ranger. Maybe he had an encounter with a powerful Pokemon as a child that inspired him. Also, put them in different situations that test their skills and values. For example, if they have to choose between saving a group of small Pokemon or chasing a powerful but rare one, it will show their priorities.
Well, it could be about their adventures together in the Pokemon world. Maybe they team up to rescue a rare Pokemon or to stop an evil team's plot. For example, they might discover a new type of Pokemon that's in danger and work to protect it.
One popular storyline could be Ben and Summer teaming up to save a rare Pokemon from a poacher. They might use their ranger skills and their unique bond to outwit the bad guys.