Mantine takes 20 additional damage from Lightning-type attacks
To save you your precious 2 hours, heres a short and sweet summary of my research from Scryfall: Greens Card advantage primarily comes from its Creatures

Good token commanders in MTG must have at least 1 of the following 3 characteristics: The ability to generate a large number of tokens at a proportionally low mana and opportunity cost Easily repeatable token generation Strong supporting effects for tokens that justify not being able to create tokens Good token commanders also can have the following traits in conjunction with the above: Fast, accessible payoffs for creating your tokens, such as giving them haste, boosting their power, or gaining effects when they die Potential for establishing infinite combos with your tokens Miscellaneous useful effects Many of the strongest token commanders have multiple traits from the lists above and contain access to green and/or white cards, as these colors have the most powerful support cards for token strategies, many of which were shown earlier
The flexibility on Farewell is awesome since you can choose to exile whatever threatens you the most, be it creatures, graveyards, or everything at once
Typically higher valued than their non-shiny counterparts (with the initial first edition Charizard card being a clear exception), these cards often trade for several hundred dollars
Nowadays, only Dark Magician and Blue-Eyes White Dragon are more recognisable, and they still hold a pedestal of power despite their legal varients competitive success