Hi, I grow up watching Japanese anime. There are a couple of them that I remember the plots but not the titles, can you guys help me?

1. This anime was set up in a fantasy style of world where a rather honest guy met a rather sassy girl, and they sort of do character change by kissing and doing 'Two-become-One'. They become a powerful hero (not sure girl or guy since the hero is made out of them both).

2. This anime was set up in a Japanese high school, where the girls' family all have super power including the sisters (the mother passed away so they only have a father who doesn't have super power). There's this guy, when the girl and the guy clashes their head, they change body.

3. This anime was set up in a fantasy world (or maybe not, just ordinary world with talent people). A scientist (not sure about this) created two robots (not sure if they're robots). The two robots are normally the size of soft toy, but they can do character change and become regular human size and really powerful. They really love fighting and always fight each other.

4. This is the last one. I think there are 3 girls who are having a school excursion to a museum (maybe not a museum) and they're sucked into a fantasy world (not sure how they get there) where there're monsters trying to take control of the world. The 3 girls have power to protect the 3 gigiantic pillars that support the world and their princess(?). They succeed and go back to the same time same place.

Please, can someone help me?