Seaking is a dragon?
Anyway, what do you think of this for an original, no starter, no legendary 1st gen team:
Are there any improvements I could make to my team?
That's mister badass Kingdra, with his Yawn and Rest combos plus his high-ish (240+) Def and Sp.Def xD. And yes, he's a Water/Dragon, meaning his only weakness is Dragon
Your team is balanced, but personally, I would exchange Raichu for Jolteon. He's one of the ultimate electric badasses.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"