Values can be confusing when you take pull rates into account. The correlation between pull rate and value isn't as direct as you think. Value is determined by supply and demand. Pull rates influence supply, but they will not be a primary factor of value.
I suggested trading the M-Kangaskhan for packs because packs are like currency on PTCGO. I almost never open packs because in general you will lose value. It will be way easier to get Enhanced Hammers, Virbank City Gyms, Super Rods, etc. if you are offering packs. Just about everybody wants packs, not as many are looking for M-Kangaskhan EX, so you are expanding your options this way.
Those cards you listed are pretty cheap as well. Most of those type of cards I can get 4 for 1 pack overnight on public trade (like Rare Candy, Rainbow Energy, Muscle Band, Float Stone, etc.), and some will be more like 2 for 1 pack (Virbank City Gym, Hypnotoxic Laser.)
I also want to clarify, not all packs are created equal. Legendary Treasures and Emerging Powers are some of the least desirable packs. Plasma Storm isn't the greatest either but people will still accept them. Also, when a new set first comes out, the packs are often worth double until the hype dies down.