There's almost too many to list and several of them are fairly accessible
Prismatic Lens- This card may provide color fixing and a little bit of ramp, but I dont think that it is good enough to fit into the deck
Warehouse Krark's Thumb Krark, the Thumbless Mana Clash Mana Crypt Mana Screw Mijae Djinn Mirror March Mirrored Depths Mogg Assassin Molten Birth Molten Sentry Mutalith Vortex Beast Negative Zone Portal Odds // Ends Odds // Ends Okaun, Eye of Chaos Orcish Captain Planar Chaos Plasma Caster Pokey, the Scallywagg (playtest) Puppet's Verdict Rakdos, the Showstopper Ral Zarek Ral, Monsoon Mage Risky Move Scoria Wurm Setzer, Wandering Gambler Skittish Valesk Skyclaw Thrash Sorcerer's Strongbox Squee's Revenge Stitch in Time Tavern Scoundrel Tavern Swindler The Gold Saucer Tide of War Unleash the Flux
For a long time, Baby Pokemon rarely got cards because of this, but in the modern era, this problem has been solved by making Baby Pokemon support Pokemon that often have little HP but useful attacks that cost no Energy
And who knows, you might even be fortunate enough to stumble upon a legendary Pokmon god pack