Water 7 and Phantom Lord. This arc is very similar, very very similar. Friends getting brutally beat up and left for dead. The people who did it hanging out in their base/bar and partying and bragging about beating them up. The protags burst in and make an entrance and proceed to beat up all the mooks in the joint. Only struggling with the top tier fighters. Although OP has a better result as Usopp didn’t fall in love with the person who beat the shit out of him Franky/Franky Family., like Levy did with Gajeel.
Cherry Blossoms and Rainbow Blossoms.The second one is very similar as well. Of course for all I know it’s based on some Japanese legend so. Anyway Both are sick they see a tree, are amazed, turns out the trees in a boat then both people get to feeling better. I’m really hoping this is based on something from japan because that’s just really similar to be a coincidence.
Chess and Mavis. Again this is very similar, the crew are traveling on a boat. There’s a person seemingly floating on the water (In Mavis’s case this may very well be.) As they approach the person starts to rise with a sphere underneath them. Of course the scenarios are different as are the things underneath them. Though it’s still visually similar.
Goodbye Vivi and Goodbye Laxus. Both the Straw Hats and Fairy Tail have a special way of saying goodbye to a good friend of theirs. Of course this is common but both were the end of an arc full of struggles.
Going Merry and Future Lucy. Once again this could merely be the translators making it similar. People also do say similar things in different series. Both were at the end of their ropes and wanted to go on more adventures.
Luffy and Natsu. On this one it’s more of the anime and probably a thematic thing. Though both are punching people really hard and are pissed off, the shading and lighting and overall scene is very similar. Of course again this is anime only and is probably for artistic value over anything.
Franky and Gajeel. I don’t have to explain this as it’s already written on that sheet.
For this one, this pretty much all Shonen protag’s of course not all, I can think of a few who are the exact opposite. Anyway they are similar and both share a red headed mentor a precious clothing item given to them by a father figure. They are also very similar in design.
Zoro and Gray. This is common in various degrees. Both did this to focus, though the fact that it’s in the same spot albeit different sides and both cut make it very similar.
Kuma and Hoteye. I mean if it was just a silhouette you wouldn’t be able to tell who is who. Kuma and Hoteye both share the same shape, carry a bible, and are huge compared to the others. They are also rather somewhat gentle.