Sweet-Gum Recluse Sweet-Gum Recluse provides a large body that synergizes with +1/+1 counter decks
Number of Colors : When you disregard budget, you find that the more colors you have in your commanders color identity, the better
Both of these Pokmon can make great use of Triple Acceleration Energy, and Im sure that creative deck builders will try to make them work
Finally, I'll point out that Marneus, Alela, and Raffine all also play into an Esper sub-theme that may be subtle, but is definitely powerful: aggro-tempo
Drawing a card the first time an artifact enters is extremely powerful
Despite being a mono-green list, Delighted Halfling and Birds of Paradise are still making the cut simply on the off-chance that your opponent's cast a spell that requires you to have differently-colored mana, and they're both at least as good as the Llanowar / Fyndhorn / Elvish Mystic trio