Water
You could say that water is weak to grass types mainly because plants use water as one of their "Ingredients" in making their "Food" as water is one of the components that activates the Photosynthesis. I would say the reason that it isn't so effective against it is because Water is the lifesource to most plants and hitting grass with water doesn't seem like anything malevolent
I would personally think that it's weakness to Electric has something to do with the fact of how dangerous it is to bring water in contact with electricity for when this happens the water will not only evaporate but electricity will notably be the most dangerous component in this reaction
I think that it resists Ice mainly because Ice is just the stable form of water and is therefore part of it
I believe that it resists itself because when water comes together, it just becomes larger meaning that it has no negative affect should it be hit b water
Grass
It's Fire weakness seems a little obvious to me mainly because Fire destrs a lot but nothing is scorched as badly as plants are by Fire. It causes ForestFires and travels extremely fast when it comes in contact with plants or leaves burning an entire area in just a pace of a few seconds
I believe that it's bug weakness comes from the fact of how many insect do not only feed if them but can fatally damage them to the extent that Leafless are even killed intentionallly due to how drastically they damage plants
I would say that it's Ice weakness can easily be compared to how Trees let their leaves fall during the Winter. When the leaves get detached, they have no food and freeze or dry out.
Mr.K: Frost Bite often kills smaller plants in fall
I have always believed that it's flying weakness had something to do with the fact that birds tend to pluck leaves or break of branches to make their nest
It's poison weakness really speaks for itself as one of the easiest ways to kill a plant is to intoxicate it
Since water and ground/earth are the one of the basic components that a plants needs to start it's life, it seems only logic that it will not be hit superffectively by it but rather resist it
Plants is general seem to rival a lot with each other, however grasses are pretty much siblings as they literary clone themselves until there is a whole field of grass. With this natural bond I could only think that it is clear why grass resists grass
Fire
Fire's weakness to Water seems obvious as well as you can easily dim out Fire with some Water
It's weakness to Ground acts in the same position as Water as a recommended way to put of Fire is to waist some sand on it
Like the 2 above it's weakness to Rock acts in a similar manner however a little differently. Rocks are also a way of dimming Fire but they also have the capability of sealing it as there is almost no better way to seal away Fire then putting underground or compressed by Rocks
Fire makes more fire so fire+fire doesn't seem to be anything malicious so I do believe that it is for this reason that they resists each other
Water and Fire are known to be long life rivals and when they both colide, it is the fire that will be quenched and the water that will evaporate so I do think that it is clearer why fire is not very effective against water
Like I mention below, rocks and stones are one of the best places to seal away fire. To accomplish this Rock must be able to resist the devastating heat of Fire
Fire can be seen as a form of powerful magic and an elemental type. Dragons are known to be impervious to any kind of magic so although Fire is a powerful form of magic, it is repelled by the Dragons
Electric
Electric's weakness to ground can be associated with the fact that electricity is nullified the moment it touches the ground as it tends to seek the fastest way to the ground
Electric works in a similar manner to fire. Electricity+more Electricity is only dangerous to us, but forms nothing bad for this powerful Force of Nature
Like Fire again Electricity can be seen as a more advanced manner of magic. Advanced or not, magic stays magic and Dragons laugh in the face of magic
Believe it or not, it has been researched and engineers have found a form of electricity in plants
Stanford engineers have generated electrical current by tapping into
the electron activity in individual algae cells. Photosynthesis
excites electrons, which can then be turned into an electrical current
using a specially designed gold electrode. This study could be the
first step toward carbon-free electricity directly from plants.
Seeing as this has no negative affect on plants, I do think this plays a role in why electric attacks are weak to grass
Dragon
In mythology there was no magic greater then that of dragon so it would seem only logic that only it is mostly rivaled by it's equal superiority.
Brotad: dragons, who are typically reptilian, there could be a biological reason for their ice weakness. Reptiles are cold-blooded, and are dependent on heat from their environment. So they sunbathe frequently and are attracted to hot areas. In colder conditions, they become sluggish, and can even die. As such, dragons take little from the heat of fire but live in terror of the deadly ice.
Dragon types are resistant to every form of the primordial elemental forces: Grass, Fire, Water, Electric. Not only are these the first elements but they are also the basic forms of magic. Like you may have guessed, dragons take magic like bosses
Ice
Like Slashy said before me I would say the most logic explanation would be that Fire melts Ice like a boss nothing more to say :P
I would say that it's fighting weakness can be brought to you by the clear fact of how easy it is to evolve Ice from order to disorder with just a twist of a hand
Rocks are very destructive and can easily make quick work of anything that is very breakable. Should a rock fall on a piece of Ice, it would surely break into many pieces.
I believe that it resist only itself since everything can easily damage Ice and or possible melt or decompose it
Rock
It's fighting weakness seems very obvious in my opinion mainly because rocks are relatively breakable and since most fighting types are humanoids(The most destructive and deadliest creature amongst all living beings) it seems to speak for itself
It's grass weakness seemed a little harder to figure out but I finally got through. If you were to plant a seed in a rock and if that seed was to be able to get all the needed resources to grow, the Rock would break mainly because the seed will not only drain out all the water but it's roots will grow out of it
I would associate it's water weakness with the fact of how it is really a double-edged sword. Although water plays a large role in the anatomy of a rock, it can be the source of it's destruction almost 80% of the time
I should say that it's ground weakness should come from the simple fact of bashing a rock against the ground...it will break somehow
Ground
I would say that it's weakness against water has a strong relationship with the fact of how water distorts it's original molecular structure turning into a muddy and when dry hard component often making it easier to break
I will associate it's grass weakness with the fact that plants act as little parasites at times as they suck every form of aquatic/mineral presence in the earth like a boss. When this is done too often and there is a low balance of occasional rain and drought, the ground will become barren.
I would say that it's weakness is for the simple fact that when Snow is present, the ground is overtaken, doesn't become visible and will stop any form of life growing out of it(with some exceptions)
Answer continued below
